Category Archives: Training

All about training… by Nick Vardavas

Shoulder pain management

As the saying goes “once bitten twice shy” or in Greek “once you burn your mouth from hot soup, you even blow on yogurt”.

Maybe a genetic predisposition, maybe playing tennis since junior high, maybe years of heavy weight lifting, I’ve been dealing here in there with my right shoulder.

Usually nothing a little rest and some external rotations wouldn’t take care of.

Ffwd late 2018 and I injure my shoulder again doing dips. Bad. This time around things were not that easy. Would lay off and do the usual treatment for a while, but as soon as I got back to training immediately I would be in pain again.

See, the shoulder is a very vulnerable and mobile joint. You have a large humerous barely fitting in a glenoid fossa.

Because it’s so highly mobile we tend to put it wrong positions. Even in everyday posture.

Shoulder pain is not always linked to the shoulder. It could be a stiff neck radiating in the shoulder.
We think we have a shoulder problem but what we have is really a posture problem. It could be overuse injuries.

The culprit? Usually rotator cuff and/or biceps tendons.

The easiest way to protect your shoulder joint think of the risk to reward ratio.
There are many things I won’t do anymore that many people love doing. Over time and with progressive resistance that strain on those soft tissue structures is gonna increase and potentially hurt you.

I’m not telling you not to do certain exercises. I am telling you to think. Exercise should protect you not hurt you.

People (and mostly older folks) usually have some problems from overstretch under loading and overusing with that load. They overstretch the bicep tendon. Exercise that you perform a horizontal abduction (think bench press, peck fly etc) will do that. Don’t overstretch your front shoulder (Don’t let the elbow fall way back past your body).

Shoulder injury management

1. Address the problem immediately
3. Exercise is imperative
4. Access your do’s and don’ts

You’d be surprised but the most common shoulder injury is a re-injury. People who have been hurt and try to get back too soon or too aggressive.

Tendons heal slower cause of their poor blood circulation. Don’t rush things.

Things to avoid:

If you have tendinitis lifting your elbow above shoulder level is not the greatest idea.
So things like lateral raises that end up too high or military raises, shoulder presses and upright rows are a no-no.

Things to do:

Strengthen external rotators, lats and low traps. That way you Create shoulder stability AND scapula function.

Many people tend to forget that poor scapula movement can predispose to injury. It must be mobile enough to allow positions needed to allow the arm to move without impingement.


1. Perform horizontal abduction exercises (that send your arms backwards) like rear delt flys, face pulls etc. That way you’ll strengthen your supraspinatus and rear delt to pull your numeral head back and up in the glenoid fossa so it’s not pinching anymore.

2. External rotation. Put your shoulder into scaption (55 degrees abduction and 30 flexion).
That’s where the joint is most open. Ideally you want to be antigravity. Preacher bench works excellent for that! External rotators stabilise the arm. Don’t forget internal rotation also!

3. Exercises that send the arm down from overhead (granted you don’t hurt by raising your arm). Try the one-arm lat pull down You’ll activate your lats that pull the arm inferiorly. As a result compression is reduced and sub-acromial space is increased.
You will also work your low traps (they help in upward rotation, posterior tilt of the scapula) assuring better scapula kinematics as you perform overhead movements.

Don’t do anything unless pain free!!

The pain is gonna go away when the inflammation goes away. Don’t forget to ICE!

That’s when you SLOWLY re-introduce your favourite pressing exercises.

Cut all intensity by 50% and do about 17 reps or so. Then increase by 20%.

Αλυσίδες. Λάστιχα. 


Διάβασες τον τίτλο και σκέφτεσαι: Ακόμα δύο “παιχνιδάκια¨ στην ατελείωτη λειτουργική λίστα εξοπλισμού Νίκο; ‘Ελα τώρα, δεν έχουμε αρκετά ήδη; Δεν σε κατηγορώ, αυτό θα σκεφτόμουν και εγώ αλλά όχι, εδώ τα πράγματα είναι αρκετά διαφορετικά.

Οι δυο τεχνικές δεν είναι καθόλου καινούργιες. Παρόλο που έγιναν διάσημες απο τον Louie Simmons και χρησιμοποιούνται κατά κύριο λόγο σε προπονήσεις δύναμης, powerlifting και υπερτροφίας είναι εξαιρετικά λειτουργικές. Κι όμως ο περισσότερος κόσμος δεν γνωρίζει για την ύπαρξη τους. Ενώ αυτοί που γνωρίζουν, από την εμπειρία μου και όσο έχω δει δεν τα χρησιμοποιούν σωστά. Είναι ένας τεμπέλης τρόπος να αποκτήσεις δύναμη; Η απάντηση δεν είναι τόσο ξεκάθαρη.

Σίγουρα δεν είναι απαραίτητη η χρήση τους αλλά αν είσαι μέσος ή προχωρημένος αθλητής, θα σε βοηθήσουν να χρησιμοποιήσεις την μέγιστη δύναμη καθόλη την επανάληψη και το εύρος κίνησης της. Είναι φοβερά εργαλεία για να σπάς plateau (σημείο στην απόδοση/δύναμη σου στο οποίο έχεις κολλήσει και δεν μπορείς να ξεπεράσεις), να ανεβάσεις την απόδοση σου. Τέλος, είναι fun!

Γιατί να τα εντάξεις στην προπόνηση σου;

Ας αρχίσουμε με το γεγονός ότι αυτά τα εργαλεία σου δίνουν προσαρμοστική αντίσταση.


Τι σημαίνει αυτό και πως θα σε βοηθήσει.  Ας πάρουμε για παράδειγμα μια άσκηση που θα χρησιμοποίησουμε αρκετά σε αυτό το άρθρο. Πιέσεις πάγκου. Είσαι ξαπλωμένος, “ξεκλειδώνεις” την μπάρα και αρχίζεις την εκτέλεση. Θα μπορούσες να σηκώσεις πολύ περισσότερο βάρος αν κατέβαζες την μπάρα μερικά εκατοστά απο την αρχική θέση αντι να την κατεβάσεις μέχρι το στήθος σου και μετά να την πιέσεις.

Άλλη άσκηση;  Καθίσματα. Αν μπορείς να σηκώσεις 100 κιλά σε ένα ολοκληρωμένο κάθισμα, πιθανόν να σήκωνες 150 σε ένα κάθισμα του ενός τετάρτου. Γιατί; Επειδή σε αυτή τη φάση της επανάληψης (“ψηλά” ή στο τέλος) είσαι (πολύ) πιο δυνατός.

Η κάθε άσκηση και μηχάνημα έχει επίσης την δική της καμπύλη αντίστασης που μπορεί να μην ταιριάζει με την δική σου καμπύλη δύναμης.


Επέτρεψε μου να σου εξηγήσω. Μπορούμε να χωρίσουμε την τροχιά μιας κίνησης σε οποιαδήποτε άσκηση και να την χωρίσουμε χοντρικά σε 3 κομμάτια: Αρχή, μέση και τέλος. Για να καταλάβεις που η αντίσταση είναι μέγιστη δεν έχεις παρά να κοιτάξεις πότε η βαρύτητα ( ή η αντίσταση) είναι κάθετη στην τροχιά της κίνησης.

Εδώ θέλω να σου επιστήσω την προσοχή: Ασχέτως αν χρησιμοποιήσεις αλυσίδες/λάστιχα, ως προπονητής/αθλητής πρέπει να σκέφτεσαι αν ο προγραμματισμός σου περιλαμβάνει ασκήσεις οι οποίες υπερφορτώνουν τον μυ σε διαφορετικά εύρη.  Ενώ παλιά ξέραμε διαφορετικά, καινούργιες έρευνες (Wakahara 2012,2013), δείχνουν ότι στοχευμένη ενεργοποίηση διαφορετικών τμημάτων ενός μυός συμπίπτει με το που υπάρχει ανάπτυξη στον συγκεκριμένο μυ. Με απλά λόγια – ενεργοποίηση διαφορετικών πτυχών ενός δεδομένου μυός μπορεί να επηρεάσει την έκταση ανάπτυξης του.

Για να έχεις λοιπόν μια ολοκληρωμένη σωματοδόμηση πρέπει να γυμνάσεις όλες τις πτυχές των μεγάλων μυών με μια ποικιλία ασκήσεων.

Σου παραθέτω 3 απλές διαφορετικές ασκήσεις δικεφάλων ως παράδειγμα

Μεγαλύτερη δυσκολία στην αρχή της κίνησης
Μέγιστη δυσκολία στο μέσο της κίνησης
Μέγιστη δυσκολία στο τέλος της κίνησης



Προσαρμοστική αντίσταση

Χρήση λάστιχων σαν και αυτά


(όχι αυτά που δίνεις να κάνει η μαμά στο σπίτι) μας επιτρέπει να τροποποιούμε την επιβαλλόμενη αντίσταση έτσι ώστε να διευκολύνουμε τα δύσκολα σημεία και να δυσκολέψουμε τα εύκολα σε μια άσκηση.

Αν βάλεις λάστιχα ή αλυσίδες και εκτελέσεις πιέσεις πάγκου, θα αισθανθείς την μπάρα να βαραίνει ενώ τη σηκώνεις. Για να προσαρμοστείς στο γεγονός της αυξανόμενης αντίστασης πρέπει να μάθεις να πιέζεις εκρηκτικά. Αυτό έχει ως αποτέλεσμα το νευρικό σου σύστημα να στρατολογεί περισσότερες κινητικές μονάδες (ομάδες μυϊκών ινών που ελέγχονται από ένα νεύρο), να ενεργοποιούνται περισσότερες τύπου ΙΙ μυϊκές ίνες που έχουν τη μεγαλύτερη προοπτική για υπερτροφία (Fry) και έκρηξη (Wilson) κάνοντας σε πιο εκρηκτικό και δυνατό αθλητή.
Σε μια έρευνα, ο Garcia-Lopez, χρησιμοποιώντας λάστιχα επιπλέον της αντίστασης κατά την εκτέλεση οριζόντιου πάγκου είχε ως αποτέλεσμα σε μεγαλύτερη περίοδο επιτάχυνσης όπως και περισσότερο έλεγχο της πλειομετρικής συγκριτικά με την εκτέλεση της ίδιας άσκησης μόνο με ελεύθερα βάρη. Τα αποτελέσματα δείχνουν ότι τα κινηματικά οφέλη χρήσης λάστιχων μαζί με ελεύθερα βάρη είναι ειδικά εφαρμόσιμα σε αθλήματα που η δύναμη και η ταχυδύναμη είναι σημαντικές παράμετροι.

Ο Anderson, σε μια έρευνα του έδειξε ότι λάστιχα σε συνδυασμό με ελεύθερα βάρη είχαν σαν αποτέλεσμα διπλάσια έως και τριπλάσια κέρδη σε δύναμη σε σύγκριση με κλασική προπόνηση αντιστάσεων (μόνο ελεύθερα βάρη) ακόμα και σε αθλητές με πολυετή (4 χρόνια) εμπειρία στην προπόνηση αντιστάσεων.

Υπερφόρτωση της πλειομετρικής

Η πλειομετρική φάση (ή αρνητική, ή το κατέβασμα) μιας άσκησης και είναι εκεί που παρατηρείται η μεγαλύτερη μυική καταστροφή και ως αποτέλεσμα και ο μύικος κάματος (πιάσιμο) που νοιώθεις μετά την προπόνηση (Kuipers). Υπό την προϋπόθεση ότι μπορείς να έχεις και την ανάλογη αποκατάσταση, περισσότερη μυϊκή καταστροφή είναι γενικά καλό. Τα λάστιχα εντείνουν την πλειομετρική συστολή σε μεγάλο βαθμό. Αν δεν κοντρολάρεις τη κίνηση, τα λάστιχα θα κατεβάσουν το βάρος γρήγορα – κάτι δυνητικά πολύ επικίνδυνο. Για αυτόν το λόγο τα λάστιχα χρήζουν μέγιστης προσοχής και πρέπει να χρησιμοποιούνται περιοδικά μόνο. Παρόλ’αυτά είναι εξαιρετικά αποτελεσματικά στην επίτευξη μυϊκής υπερτροφίας. Καλά παραδείγματα για εφαρμογή των προαναφερθέντων – πιέσεις πάγκου και πρέσσα ποδιών.

Τα λάστιχα μπορούν να διευκολύνουν μια άσκηση. Μπορείς να τα δέσεις σε ένα μονόζυγο για να κάνεις τις έλξεις εφικτές ή πιο εύκολες. Με τον ίδιο τρόπο μπορείς να τα χρησιμοποιήσεις για να διευκολύνεις την εκτέλεση των pushups. Άλλες εφαρμογές είναι για πάγκο ή squat μέσα σε power rack. Η καμπύλη αντίστασης αλλάζει σε γραμμική χωρίς αδύναμα σημεία στην εκτέλεση. Ως αποτέλεσμα, παρατείνεις το σετ με περισσότερα κιλά, αυξάνοντας την έκθεση των μυών σου σε αυτό!
Δυνατότερη μυική σύσπαση

Επειδή τα λάστιχα μπορούν να προσαρμόσουν την επιβαλλόμενη αντίσταση μπορούν να επηρεάσουν το μοτίβο ενεργοποίησης και την αίσθηση της κίνησης. Για να το καταλάβεις προσπάθησε να εκτελέσεις πιέσεις στήθους σε μηχάνημα (τύπου hammer).


Μπορείς επίσης να τα χρησιμοποιήσεις με αλτήρες για να αλλάξεις την γωνία έλξης και κατ’επέκταση την ενεργοποίηση (Schulthies).
Αν η χρήση λάστιχων και αλυσίδων έχει ως αποτέλεσμα μεγαλύτερη επιφόρτωση και δυναμικά κέρδη, εξυπακούεται ότι θα αποτελέσει μεγαλύτερο έναυσμα για μυική υπερτροφία (Ghigiarelli).
Διευκόλυνση περαιτέρω επαναλήψεων

Υπάρχουν ορισμένες ασκήσεις που απλά “νοιώθουν” καλύτερα σε υψηλές επαναλήψεις όταν τις κάνεις με λάστιχα παρά με ελεύθερα. Δύο από αυτές η αγαπημένη face pull και οι πλάγιες εκτάσεις για ώμους.

Επειδή τα λάστιχα διευκολύνουν την αντίσταση, σου επιτρέπουν να νοιώσεις την τάση σε κινήσεις που δεν μπορείς με άλλο τρόπο. Η κλασική “Over and back” διάταση γίνεται πολύ πιο αποτελεσματική. Επίσης η χρήση τους είναι πολύ καλή στην ενεργοποίηση των έξω στροφών της ωμικής ζώνης. Όσον αφορά τραυματισμούς (πρόσθιο χιαστό) και αποκατάσαση, οι αλυσίδες δουλεύουν εξαιρετικά. Το καλύτερο post rehab είναι με βάρος αλυσίδας και αυτό γιατί όπως είπαμε δουλεύει συνεργιστικά με την καμπύλη δύναμης. Μπορείς λοιπόν να αρχίσεις μια προπόνηση αποκατάστασης μόνο με αλυσίδες και να συνεχίσεις σε μετάβαση σε ελεύθερα βάρη μετά από ένα διάστημα. Κράτα τις αλυσίδες και παράλληλα φόρτωνε “κλασικά” κιλά όσο ο πελάτης δυναμώνει.
Οι αλυσίδες λειτουργούν παρόμοια. Η διαφορά είναι ότι τα λάστιχα επιταχύνουν την πλειομετρική φάση της εκτέλεσης (εξαιρετικά για έκρηξη/ταχυδύναμη). Όπως ανεβάζεις τη μπάρα, πιο πολλοί σύνδεσμοι σηκώνονται από το πάτωμα προσθέτοντας αντίσταση στην άσκηση – φόρτωση(εκεί που είσαι πιο δυνατός) και στο κατέβασμα το αντίθετο – εκφόρτωση. Επειδή όμως δεν έχουν το ελαστικό συστατικό που έχουν τα λάστιχα, δεν δίνουν την ίδια τάση και ως (θετικό) αποτέλεσμα δεν καταπονούν το μυϊκό και νευρικό σύστημα το ίδιο. Δεν μπορείς να τις χρησιμοποιήσεις σε όλες τις ασκήσεις. Διάλεξε ασκήσεις που παράγουν τάση μέσω έκτασης.
Το πρόβλημα με τις αλυσίδες είναι ότι ο περισσότερος κόσμος δεν τις χρησιμοποιεί σωστά. Όπως είχα αναφέρει και πριν, όπως και τα λάστιχα έτσι και οι αλυσίδες βασίζονται στην προσαρμοστική αντίσταση. Που σημαίνει ότι σε δυσκολεύουν στο σημείο που γίνεσαι πιο δυνατός. Το φορτίο δηλαδή στη μπάρα προσαρμόζει την καμπύλη δύναμης σε όλο το εύρος της κίνησης. Για να μεγιστοποιήσεις όμως αυτό το φαινόμενο, αλυσίδες (σημασία ο πληθυντικός!) πρέπει να προσαρμοστούν σε μια μικρότερη αλυσίδα.


Αν χρησιμοποιείς μόνο μια αλυσίδα που ζυγίζει υποθετικά 10 κιλά δεν υπάρχει εκφόρτωση στο κομμάτι που κρέμεται και δεν ακουμπάει στο πάτωμα. Γιατί; Ο κάθε κρίκος ζυγίζει περίπου 1-2.5 κιλά. Αν χρησιμοποιήσεις λοιπόν μια αλυσίδα πόση φόρτωση-εκφόρτωση θα επιτύχεις?


Εδώ ψάχνουμε για 40-50 κιλά φόρτιση-εκφόρτιση!! Αν το κάνεις, κάντο σωστά!
Προσθέτοντας αλυσίδες στον οριζόντιο πάγκο αυξάνει τη μέγιστη προσπάθεια επιτάχυνσης της μπάρας. Αυτό μπορεί να οφείλεται στο γεγονός ότι οι αλυσίδες επιτρέπουν ταχύτερο κύκλο διάτασης-βράγχυνσης (η στιγμή που η μπάρα αλλάζει κατεύθυνση από την πλειομετρική σε μυομετρική ή αλλιώς από το κατέβασμα στην πίεση) και κατ’αυτό τον τρόπο ενεργοποιόντας μυική μεταδιεργετική ενεργοποίηση η οποία αυξάνει τη δύναμη της μυϊκής σύσπασης (Baker).

Έξτρα εφαρμογές

  • Χρησιμοποίησε τις αλυσίδες σκέτες αντί για κλασικά κιλά για υπερφόρτιση σταθεροποίησης, ή για μικρές αλλαγές μέσα στο πρόγραμμα σου, μια τεχνική που βλέπουμε σε προπονήσεις “chaos”. Προσπάθησε πιέσεις ώμων οι απαγωγές.
  • Πρόσθεσε τις σε pushups ή έλξεις και όσο κουράζεσαι άρχισε να αφαιρείς (φυσικά χρειάζεσαι ένα φίλο εδώ) για καταπληκτικά strip sets!



  • Hip thrusts με λάστιχα ή αλυσίδες θα υπερφορτώσουν τους γλουτούς.  Ιδανικά με hip thruster όπως βλέπεις στη φώτο. Ο μόνος χώρος που ξέρω ότι το διαθέτει στην Ελλάδα είναι το body solutions του Γιώργου Γεωργά (ένας απο τους λίγους εξαιρετικούς γυμναστές που γνωρίζω).


Εξαιρετικό στο να μάθει κάποιος τι σημαίνει να πιέζει σκληρά και γρήγορα. Είτε είναι αθλητής είτε ένας απλός ασκούμενος.

Σημαντικό: Όχι παραπάνω από 2, το πολύ 3 εβδομάδες προπόνησης ειδικά για λάστιχα. Μετά θα αρχίσουν να σε κουράζουν λόγω της μυϊκής υπερφόρτωσης. Αλυσίδες μπορεί να χρησιμοποιηθούν πολύ περισσότερο. Δεν χρειάζονται την ίδια προπονητική προσοχή και περιοδισμό.

Καλή διασκέδαση!



Wakahara T. “Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training”. Eur J Appl Physiol. 2012 Apr;112(4):1569-76

Wakahara T. “Nonuniform muscle hypertrophy: its relation to muscle activation in training session”. Med Sci Sports Exerc. 2013 Nov;45(11):2158-65.

Fry, A.C. “The role of resistance exercise intensity on muscle fibre adaptations”. Sports Med, 2004. 34(10): p. 663-79.

Wilson, J.M., et al. “The effects of endurance, strength, and power training on muscle fiber type shifting”. J Strength Cond Res, 2012. 26(6): p. 1724-9.

Garcia-Lopez, D., et al. “Free-weight augmentation with elastic bands improves bench-press kinematics in professional rugby players”. J Strength Cond Res, 2014.

Anderson, C.E., et al. “The effects of combining elastic and free weight resistance on strength and power in athletes”. J Strength Cond Res, 2008. 22(2): p. 567-74.

Kuipers, H. “Exercise-induced muscle damage”. Int.J Sports Med, 1994. 15: p. 132-135.

Schulthies, S.S., et al.  “An Electromyographic Investigation of 4 Elastic-Tubing Closed Kinetic Chain Exercises After Anterior Cruciate Ligament Reconstruction”. Journal of Athletic Training, 1998. 33(4): p. 328-335.

Ghigiarelli, J.J., et al. “The effects of a 7-week heavy elastic band and weight chain program on upper-body strength and upper-body power in a sample of division 1-AA football players”. J Strength Cond Res, 2009. 23(3): p. 756-64.

Baker, D. “A Series of Studies on the Training of High-Intensity Muscle Power in Rugby League Football Players”. The Journal of Strength & Conditioning Research, 2001. 15(2): p. 198-209.

The Case of the Squat Part II

Technique, Myths and Problems.

 If it’s broken, fix it. If it isn’t, don’t.

If someone needs improving in their squat that would be me. Nevertheless the fact that this particular exercise has eluded me and caused me so much frustration has made me obsessed with it.

Now that we have gotten out the biomechanics part of the squat lets move onto squat technique, myths, and how to solve some common problems (if they can be fixed that is).


“Leave your ego at the locker room” and “your psychological baggage at the front desk”

If I had to say one thing about exercise technique and attitude you just read it. Most men that I see in the gym (especially in Greece) seem to think that the more weight they can lift the more macho they are. And that goes with the attitude also. You know what I mean and you’ve seen it for sure. I call it “hot eggs under the armpits” attitude. Dude relax (your arms, traps, shoulders), my girlfriend lifts (correctly) more than you. And its ok.

If there are 4 things that limit your progress in any exercise that would be mobility, technique, motor control and muscle imbalances. Wrong technique not only could result in injury but biomechanically places you in a less then optimal position to lift as much weight as humanly possible.

In a nutshell if you can’t perform an exercise with perfect technique you are doing yourself a disservice by loading it with extra weight. Especially weight you can’t handle. As Gray Cook would say “you are adding strength to dysfunction”.

Lets move on to squat technique. As just mentioned, you need to coach your athlete or client (this doesn’t apply to trainers only but to people who want to do it themselves) how to correctly squat without weight.

Before you start:

Foot placement should be about shoulder width. Too wide you’ll stretch your adductors too soon and that will probably prevent you from going too deep (that type of squat – the sumo squat, nevertheless is excellent at activating the adductors due to the light stretch/length tension relationship)

Whatever feels more natural is what I say. People differ widely here. Longer femurs will more probably require a wider stance. Long torso/short femur another possibility and you want to go much narrower.

Other things that can affect foot stance would be hip width, flexibility of hamstrings, adductors and calves to name a few. Also if your pelvic anatomy is not ideal (how your acetabulum is shaped and the way the femur fits in it) you’d probably want to go wider unless you want to suffer from acetabulofemoral impingement. More on that below.


Start the descent by bending at the knees and hips in an even motion. Your center of gravity should be in the middle of your foot. People that tend to break too much at the knees can be coached to descent thinking they are going to sit back in a chair and to shift their weight at the heels.

Go all the way to the bottom or as far as it is comfortable for you. Going in a deep squat is ideal as you activate more musculature especially the hamstrings, which are a biarticular muscle.

Even though I hate “sayings” I have to agree with “half squats = half muscle”. You can’t expect to activate your glutes and hamstrings properly when you stop at just parallel (femur relative to the floor). If you want to target only your quadriceps the ideal stopping point would be at 90 degrees.

Myth #1

You shouldn’t squat below parallel (deep squat)

Parallel squat

Its been haunting me since I can remember. Its time to put this one to rest. You should squat as low as you can and your mobility, and anthropometry will allow you. If you can go properly beyond parallel you should. A deep squat is when the pelvis has dropped below the level of the knee. Don’t pay attention to sayings like ass to the grass etc. In a full squat, the hamstrings are covering most of the calves. I know of few people that can demonstrate that correctly. Key word correctly.

Full Squat
Full Squat

The theory that deep squats pose an injury risk can be attributed to studies conducted by Karl Klein at the University of Texas. Klein noted that weightlifters that frequently performed deep squats displayed an increased incidence of laxity in the collateral and anterior cruciate ligaments compared to a control group that did not (8). Klein concluded that squatting below parallel had a detrimental effect on ligament stability and should therefore be discouraged. Soon thereafter, the AMA came out with a position statement cautioning against the performance of deep knee exercises because of their potential for severe injury to the internal and supporting structures of the knee joint.

Further research has disproved Klein’s findings, proving no correlation between deep squatting and injury risk (5,6,7). On the contary, there is some evidence that those who perform deep squats have increased stability of the knee joint. In a study, Chandler, et al. found that male powerlifters, many of them elite class, demonstrated significantly tighter joint capsules compared to controls (8).

“Provided that technique is learned accurately under expert supervision and with progressive training loads, the deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity” (4)

So we can conclude that “contrary to commonly voiced concern, deep squats do not contribute increased risk of injury to passive tissues” (4).

Case closed.

Myth #2

Can’t let the knees go past your toes/bad for knees


That’s another one that doesn’t refuse to die. Toes for most people are going to be slightly or more in front of their toes and that is OK too! I know some of you are freaking out and think I’m full of it but bare with me.

What we need to understand is everyone has different anthropometry. What that means is that people have different femur: tibia ratio. People with longer femurs will probably extend their knees several inches past their toes.

The only potential problem with letting your knees go forward is not destroying them. It is that you most likely will not be able to drive with your hips out of the “hole” (bottom position of a deep squat), which means less glute and less hamstring activation.

Remember: It’s a balanced act! Hopefully now you understand what I meant by the squat is possibly one of the MOST functional exercises ever.

Fry noted that “Although restricting forward movement of the knees may minimise stress on the knees, it is likely that forces are inappropriately transferred to the hips and low-back region. Thus, appropriate joint loading during this exercise may require the knees to move slightly past the toes.” (2)

As long as you don’t relax at the bottom position so the knee joint doesn’t open exposing the connective tissue to stress levels higher than their tensile strength you’ll be ok. Doesn’t mean you can’t pause at the bottom, just keep the tension.

On the previous article we mentioned that the front squat is actually easier and safer on the knees. The very same exercise that is going to force you to extend past your toes more than any other variation!

Try telling him: “huh excuse me kind sir but should you be letting your knees to go past your toes?” I’m not liable for the answer/outcome!!

Once you reach the bottom, there is only one way: UP. What you want to do at this point is to drive your hips up and forward and at the same time extend at the knees while keeping your chest up. Too much drive at the hips though will turn this into a deadlift, too much knee action and you shift shearing forces forward. It needs to be a coordinated affair.

So there you have it. This is all you have to do. It may look simple in paper, but in fact, there are a couple of things that can and WILL go wrong with people squatting that you definitely need to address in order to be safe, and effective. Here are the ones I think are most important:


 1. Butt Wink (gym lingo)

butt wink

Aka posterior pelvic tilt. Some people as they reach the low position of the squat, they will not be able to keep their spines in the desired neutral position and the lumbar spine will start to go into flexion.

This is important cause that is another reason why squats get a bad rep.

Myth #3

Squats will wreck your back

Letting the lumbar spine go into flexion can stretch the ligaments and ultimately cause a disk to bulge. Result? Anything from a slight pain that an ibuprofen can fix, all the way to bulging disks that may even require surgery.

 a. Cause

Possibilities: one belief is that it’s a flexibility issue. Mainly that your hamstrings are tight. They claim that as you descent in the squat the hamstrings (the part that attaches to your pelvis) compete for pelvic rotation with your lumbar extensors. So if you have weak extensors your tight hamstrings will pull your pelvis into a posterior pelvic tilt. I’m not totally convinced on this one. Hamstrings are actually SHORTENED at the knee in the descent so if you think about it there is no net stretch.


Second idea is that it is anatomical. Two things could be happening here. Your femur head and your acetabulum could be shaped in a way that when you flex your hips they imping early before adequate flexion can be achieved (Pic 1,2).

Pic 1. The femur and how it fits into the acetabulum of the hip


Pic 2. Two ways in which an anatomic deformity of the femoral head and the acetabular ridge can lead to impingement (10)
Pic 2. Two ways in which an anatomic deformity of the femoral head and the acetabular ridge can lead to impingement (10)

Also, it could be that your anterior superior iliac spine (ASIS) jams against your femur impinging your iliopsoas. Many people will complain of pain. They are not lying. (1,10).

b. Solution

A wider stance (as wide as you need according to anthropometry) will fix the femoral/acetabulum/ASIS possibility. Combine that with some good stretching of the hamstrings and you are on your way to greatness. The fastest way to mobility and flexibility is by manual work. I can’t stress how important it for people who exercise regularly to get a good massage. Preferably ART (Active Release Technique).

One quick footnote here: If it (the butt wink) happens close to parallel and its not so dramatic its ok, if its too much and you’re getting close to limit of lumbar flexion (ligaments, herniation) then no. Only experience can show that. Some people tend to overestimate their assessments. That will only hold an athlete back. Being safe is a priority but exaggerating can be a handicap.

2. Heels Raise from the floor

You will often notice that some people raise their heels when they descent low enough in a squat. Especially, if they are trying to keep their lumbar spine straight.

a. Cause

This is possibly a mobility issue in the ankle. Another possibility is tightness in the soleus muscle. Some people will say that the calves are tight. I’m not really convinced as the gastrocnemius is a bi articular muscle and during a squat descent it is actually shortened at the knee joint (same thing as the hamstrings). Another cause could be injury. One of my best clients and good friends has metal screws and plates in his tibia that prevent dorsiflexion in his left ankle.

The take-home message: if your tibia can’t travel enough forward due to any or a combination of the reasons mentioned above two things are going to happen. Either you will raise your heels or you will have to lean forward excessively. Why? Because you can’t expect to be able to balance (not fall on your ass) while your tibia stays close to vertical (relative to the floor). Unless you defy the laws of gravity. In that case I really want to meet you (feel free to contact me!).

b. Solution

Work on ankle mobility and stretch the soleus. In the meantime have your client wear weightlifting shoes or step on plates and/or a wooden platform. What this will do is it will shift the tibia forward to compensate for the lack of dorsiflexion.

Another thing to try here is front loading the client. Goblet squats are a great squat variation that fix heel lift and forward leaning most of the time. The name goblet comes from the fact that you hold a dumbbell to your chest as a goblet. The neat thing is that the dumbbell needs to make contact in two places: Chest and abs. Talk about killing two birds with one stone. Holding the dumbbell in front, someone with bad ankle mobility can keep his/her heels on the floor because the weight acts as a balance. At the same time, if they lean too much forward inevitably they would loose point of contact in the abs so they have a point of reference. Some people (example my friend) will ALWAYS have to do that. Nevertheless with a couple of modifications he clearly demonstrates a perfect squat that I am envy of (video).

 3. Knee Valgus

Many people’s knees will “collapse” during a squat, especially on the way up. Keeping your knees out during a squat is essential for 2 reasons.

If the knees track medially to the feet during the squat it increases the q angle. This refers to the angle that your femur forms in relation to your hips and to be more specific your anterior superior iliac spine (ASIS). Anything less that 165 degrees and you have a condition called knee valgus.


In women naturally this angle is narrower because of the fact that women have wider hips than men.

When this occurs, chances of encountering chronic knee injury – such as patellofemoral pain syndrome (PFPS), knee osteoarthritis, medial collateral ligament sprains, and damage to the knee cartilage and meniscus – all increase. Just a 10 degree shift in Q angle increased patellofemoral contact forces by 45% (9).

a. Cause

The main stabilisers of your femur as it relates to your knee joint are your gluteus medius and your VMO (vastus medialis obliqus). Unless the problem is anatomical these two players are weak. More that probably, your adductors are tight as well, as your TFL, lateral gastrocnemius and bicep femoris.

b. Solution

The key to the squat is glute and external rotators activation. Some people have a hard time activating their glutes to say the least.

Actively voicing to the client to keep their knees out (after you have demonstrated how of course) and using your hands to point which way the knees should be facing, will usually work.

If it doesn’t, a nice little trick is placing a piece of theraband just bellow the knee of the client. To prevent valgus the client has to engage the glutes to perform external rotation at the hips.

There are other ways like placing blocks on the outside of the clients foot that he/she has to touch with their knees but not knock over etc.

Assistant exercises to work the gluteus medius (all kinds of hip abductions) and variations of the squat to target the VMO like the infamous 1 and ¼ cyclist squat are a must. Stretching the adductors, gastrocnemius and TFL completes the package.

Pic 7. Knee Valgus αριστερά και "γόνατα έξω" δεξιά.

I want to close this (lengthy) article by stressing two things. As I mentioned earlier, anthropometry will play a huge role in squat performance. Certainly not everyone will be able to perform a deep squat, even more so a full squat, with perfect form. Don’t sacrifice quality. If someone can’t execute perfectly don’t load him or her until they can. There are many alternatives that produce identical if not comparable results. My favorites are unilateral movement (lunges, step ups, split squats etc). Don’t let ego get in the way of safety and performance.

The second is that the lists of problems is by no means exclusive nor are the solutions. As you progress in your training (if you are a lifter) or in your career (as a trainer) you’ll come across different scenarios that are going to challenge you and broaden your knowledge.

So between all this “tricks” or “solutions” you could possibly get a perfect squat out of most the first time around!

  1. Rippetoe, Mark and Stef Bradford. Starting Strength Basic Barbell Training 3rd Edition. Wichita Falls, Texas: The Aasgaard Company, 2011. Kindle.
  2. Fry AC, Smith CJ, and Schilling BK. Effect of knee position on hip and knee torques during the barbell squat. J Strength Cond Res 17: 629-633, 2003.
  3. Hirth CJ. Clinical movement analysis to identify muscle imbalances and guide exercise. Athl Ther Today 12: 10-14, 2007.
  4. Hartmann H, Wirth K, Klusemann M. Analysis of the load on the knee joint and vertebral column with changes in squatting depth and weight load. Sports Med. 2013 Oct;43(10):993-1008
  5. Meyers E. Effect of selected exercise variables on ligament stability and flexibility of the knee. Research Quarterly. 42(4):411 – 422. 1971.
  6. Panariello R, Backus S, Parker J. The effect of the squat exercise on anterior-posterior knee translation in professional football players. AmericanJournal of Sports Medicine. 22(6):768 – 773. 1994.
  7. Steiner M, Grana W, Chilag K, and Schelberg-Karnes E. The effect of exercise on anterior-posterior knee laxity. American Journal of Sports Medicine.14(1):24 – 29. 1986.
  8. Chandler T, Wilson G, and Stone M. The effect of the squat exercise on knee stability. Medicine and Science in Sports and Exercise. 21(3):299 –303. 1989.
  9. Mizuno Y, Kumagai M, Mattessich et al. Q-angle influeces tibiofemoral and patellofemoral kinematics. J of Orthop Res 2001; 19:834-40.
  10. Norkin, Cynthia and Pamela Levangie. Joint Structure and Function: A Comprehensive Analysis. Philadelphia: F.A. Davis Company, 1983. Print.


The Case of the Squat Part I

Whether you want more booty or quads, being a mechanic can alter your squat perception.

One of the most misunderstood and abused exercises that I see in the gym is the squat. While being an amazing total body exercise (placing emphasis in the lower body of course) technique can make it one of the worst, with serious consequences. In this first part I’m going to show you how different body positions can alter things.

3 main variations of the squat:

High bar squat, low bar squat and the front squat. Most people when they think about squatting think quads. With a little knowledge of biomechanics though, you will realise how the above variations place emphasis on different musculature! I’ll try not to bore you with too much science. Here goes:


In any given exercise there are points of rotation (POR) or fulcrums. In our discussion the ones of interest are the hip and the knee joint. When you come up from the bottom position of a squat, you perform extension at both of these joints (POR). Hip extensors are the glutes and hamstrings aka the “posterior chain”. Knee extensors are the quadriceps. In order to do that, you need to overcome some external resistance be that your bodyweight or some form of extra resistance (barbell).


A moment arm is the distance between a POR (hips, knee) and the point at which the rotational force is applied (in this case the barbell or to be precise gravity acting on the barbell), measured at 90 degrees from the point of force application (Fig.1)

Figure 1

The moment force is expressed in M= F (force applied to the bar) x d (length of moment arm). The magnitude of M tells us how much the object (knee, hips) is striving to turn. Shit that was boring! Bear with me….

From the equation we realize that the greater the distance of the rotational force from the fulcrum the greater the moment arm (that’s what we want!) Just imagine having a small ass wrench opposed to a big ol’ one to try and screw a bolt. I’ll take the big one any day!!

 Length Tension

For muscle to contract, crossbridges must be formed between the myofilaments. Crossbridge formation is prevented either by excessive lengthening or shortening of the sarcomere. Maximum tension and therefore force can be achieved when muscle is slightly lengthened or about 120% of its resting length. In layman’s terms you need to slightly stretch a muscle that you want to maximally activate.

I can hear you snoring already. Ok, ok I’ll shut up. Trust me, this is more info than you’ll ever need! That’s all for your plumbing course…err…. biomechanics I meant!

We got wrenches we got bolts! Let’s put theory into practice and make something happen!

As mentioned earlier we have 3 squat variations:


1 2
Figure 2



Pic. 1

The name refers to the fact that the bar sits low on the back. How low? The lowest safest position is right below the spine of the scapula (Pic 1). Any lower than that and the bar would be difficult to handle with appreciable weight loaded on it. So let’s apply the aforementioned knowledge on this type of squat. It is obvious that in order not to fall backward and to keep our base of support over the midfoot (that’s were it should always be when squatting) you will need to lean more forward. What this does:

  1. The back  can be more horizontal relative to the floor, which means that there is a better lever relative to the hips, so the posterior chain does the work. Think hamstrings and glutes. Back gets a beating too, especially the lower part.
  2. The hamstrings are a biarticular (crosses two joints) muscle, which cross the hips and the knees. On the bottom position of the squat we can see that they are shortened at the knee joint. Therefore, in order to maximize hamstring involvement we need to at least stretch them at the hip end. Bending more forward accomplishes just that. Glutes get a better stretch as well.


Figure 3


Pic. 2

High bar is the style that you will see more often in the gym. For a novice it feels a little more natural and it’s not as tricky in the execution. In this type of squat the bar sits higher on the upper traps (pic. 2). In order for the lifter to balance and not fall face forward, (as much as it would be tempting to watch) he/she is forced to stay more upright. The result:

  1. The back is more vertical; therefore the lever is more advantageous to the knee. This type of squat places more emphasis in the anterior chain (or the quads).
  2. Because of the fact that the athlete stays more upright, the knee angle is more closed therefore we get a slight stretch on the quads, whereas the hip angle is more open therefore less activation of the hamstrings and glutes.
Figure 4

Front Squat

Pic. 3

The front squat puts the lifter in an even more upright position than the other two variations. What this does, it lessens the torque (forward lean), compression (high spinal loads) and flexion. A recent study (5) also shows that the front squat works the quads harder with less stress on the knees. It is also shown to be more effective at activating the vastus lateralis and the rectus femoris. An excellent variation is the goblet squat, which I am going to analyze on the second instalment of the squat series.

  1. Back is as vertical as possible to compensate for the weight that rests in front of the body so the base of support can be kept over midfoot. That makes the moment arm of the knee more favorable.
  2. Knee angle is even more closed and hip angle remains relatively open. This activates the quads maximally.


Figure 5

But wait. What do I do?

One variation does not cancel the other. It all depends on:

  1. Who your client is
  2. His/her needs
  3. What limitations he/she has (joint health, mobility, muscle imbalances, technical proficiency)
  4. Goals (sports, general fitness etc)

Powerlifters mainly use low bar squats. It increases forward leaning, puts more emphasis on the posterior chain and a greater stress on the back muscles. Glutes are the most powerful muscle in the body (hint: want more booty? Stick with low bar!). This type of squat is probably going to allow you to push the most weight.

Actually in order of difficulty (not technical necessarily) it goes like this: Low bar, high bar, front (easier to harder). If your goal is physic enhancement or transference to Oly lifts I would stick to the high bar and especially front squats.

My advice? Unless your client is an athlete of a specific sport that would benefit strictly from the use of one, I would use them all to activate as much muscle fibers as possible while taking the following under consideration:

For a client that has poor glute and/or posterior chain activation I would probably stick with a low bar squat. On the other hand, if low back pain was a problem and technique was an issue I would stay away from them (low bar). As mentioned earlier biomechanical analysis indicates that the front squat places less compressive forces on the knees. Therefore an athlete/client with knee problems/sensitivity should probably stick to a more upright squat.

Coming up: Squat myths and how to solve squat technique problems. See you soon!


1. Baechle TR and Earle R. Essentials of Strength and Conditioning (2nd ed). Champaign: Human Kinetics, 2000. Print.

2. Rippetoe, Mark and Stef Bradford. Starting Strength Basic Barbell Training 3rd Edition. Wichita Falls, Texas: The Aasgaard Company, 2011. Kindle.

3. Wirhed, Rolf. Athletic Ability and the Anatomy of Motion. Orebro, Sweden: Harpoon Publications AB, 1984. Print.

4. Thompson, Walter R. ACSM’S Resources for the Personal Trainer. Baltimore, MD: Lippincott Williams & Wilkings, 2010. Print.

5. Gullett JC, Tillman MD, Gutierrez GM, Chow JW. A biomechanical comparison of back and front squats in healthy trained individuals. Journal of Strength and Conditioning Research. 2009 Jan;23(1):284-92.

6. Boyle, Michael. Advances in Functional Training: Training techniques for Coaches, Personal Trainers and Athletes. Santa Cruz, California: On Target Publications, December 2011. Kindle.

What the hell is “functional” training?

“Loyalty to petrified opinion never broke a chain or freed a human soul” – Mark Twain

I lived most of my life seems like in the US. Back in 2007 when I moved back to Greece I felt I was light years ahead of the info pertaining to anything training.  I was talking about functional training and people were looking at me like I had just landed from the mothership…

Things have changed since then. Im afraid for the worst.  I’ll prove my point.

I hear people (and when I mean people I mean other trainers and recreational gym goers) talking about functional training and I realize that functional training is associated with three things:

1. The props used

2. Core training

3. Void of machines/bodybuilding

  1. Toys

Much of the equipment that we often see in “functional” training (wobble boards, bosu, physio balls, airex pads, half foam rolls to name a few) has its origin in physical therapy and rehabilitation.  What we need to understand though is that functional is not so much about these gadgets per se but about the knowledge that physical therapists have gained as to prevent or (to be more accurate) reduce injury. It’s about the information why injuries occur.

These props usually place emphasis on the stabilizer muscles by creating safely unstable environments (muscles that primarily stabilize a joint), which happen to be the ones that usually get injured.  It is a well-known fact that after injury the body’s proprioception goes down the drain in the adjacent joints that got injured. Rehabilitating a client with various equipment that promotes proprioception is great. Supplementing a strength training program is also very beneficial with this type of equipment. But I see this being the main star in many cases. Ask yourself this question: How functional is this REALLY for my client…..image1

2. And then comes the core…

“I see dead people” people trying to balance on one foot on a BOSU ball, trying to do a push up with both hands and feet on a physioball at the same time. All kinds of circus acts for what? All in the name of CORE training. In fact, this is not necessarily considered core training. It’s more balance training than anything else. More show than substance.

The thing is that balance training is very very specific. What does that mean? If you learn how to balance on a dyna-disk doing squats, well you’re going to be good at exactly that. Not much else!

Don’t take me wrong! Balance training is something really important in a well-constructed fitness program. Its just overemphasized and in some cases performed with the wrong application.

Performing any strength exercise on an unstable surface is just silly and underproductive. A strength exercise as the name implies needs to focus on strength. You can’t focus on strength AND try to balance at the same time.  Its really simple: Any major strength exercise that could be considered functional has one important feature. You should be able to fall down while you’re doing it so you don’t. Balance. Coordination.  On the ground. Period.image2

Another misconception is that the core is your abs and spinal erectors when in reality the core encompasses local and global stabilizers such as the glutes, adductors and movement muscles as the lats, hamstrings and quads. So the squat for example could be considered the best functional, core and strength exercise ever. Talk about bang for your buck!! You really don’t need to overcomplicate things!

So props like battle ropes, TRX, sand bags, kettlebells all place an extra payload on the core. In which way you ask? In a stabilizing way. They capitalize in the “functional” Part of your core’s function, which is to resist rotation and extension. So trying to keep your torso as stable as possible while performing with these gadgets does exactly that. Use them with a purpose (their purpose) and not just for show and variation or in many cases unfortunately – marketing.

3. Are machines evil?

I tend to stay away from them usually but they have their place. So if leg extensions for example help elderly people move without their canes (that holds true) does that make the specific exercise non functional? Of course NOT.  Just because in real life your leg will never perform a movement like trying to walk while someone is pulling on your ankle (except in a safari gone bad) doesn’t mean that the strength you will develop for that specific exercise will not transfer in something so vital and functional as a daily activity for an elderly person.

In the same sense people differentiate between functional training and strength training/bodybuilding. As if bodybuilders don’t perform functional exercises!!!image3

They squat, they deadlift, they press overhead heavy objects; they do chin-ups, lunges (list can go on and on). In many cases a well-trained bodybuilder is MUCH more functional from a person who has relied on using only his bodyweight and the variety of the aforementioned props. Hint: a bigger muscle attacks the bone in a much preferential line of pull (more vertical) therefore creating a better lever and less torque.

People though, when they think and look at this type of training they only focus on the various machines and isolating exercises as bicep curls and don’t see the bigger picture…

We can therefore argue that the term functional should not be associated with the type of exercise, training or equipment but with the outcome instead.image4

So what IS FUNCTIONAL Training?

Any the aforementioned can produce a functional result but they fail to provide a definition and a WHY that is so. So what the hell is functional training?

Functional is an authentic outcome.  It’s a non-isolating (isolating is partial) stabilizing, pain free movement through a purposeful range of motion. Functional is symmetrical and unrestricted movement patterns.

Functional exercise then, is exercise that displays a certain amount of carryover into other activities.  So by doing it you don’t’ only improve your ability to perform the actual exercise but also other physical movements not directly practiced.  In sports training using exercises that mimic the exact sport movement  under load is not functional.

Let me explain: You don’t train a boxer by having him hold dumbbells and recreating a direct punch. A direct punch is practically a horizontal adduction/flexion of the shoulder. Instead, you train the athlete with heavy and or explosive exercises such as the bench press and the overhead press. Then sit back and enjoy what that (functional) training did in terms of carryover in his sport.

Functional is therefore a continuum and depends on the individual and the task performed. Of course that means a different thing for different people (Ex. Elderly people who spend most of their time in what is called activities of daily living (ADLs) are going to be trained quite differently from a 26 year old linebacker.  Functional is anywhere between performance enhancement to physical therapy. A coach that doesn’t use this type of training is a coach that doesn’t realize what injury prevention is.

Once you start thinking in terms of functional anatomy which simply means that the body is not a contortion of muscles acting individually you will realize that functional is simply something that stresses your muscles in all planes of motion and in all of their function which are the accelerating, decelerating and stabilizing aspect, things are going to fall in place.

Many of us have detached from that and see only through the scope of our preferred discipline.  Old school versus functional.  Thing is that we forget that the human body hasn’t really changed that much over the years.  Take cross fit for example. Uses Olympic lifting. I used to coach some of my clients with these lifts 10, 15 years ago. They thought I was crazy. People know about competitive weightlifting exercises for years.  But how popular was the snatch back then? Its just athletic concepts that have migrated in the fitness field because someone is really good at marketing.

My advice: try to stay away from the latest fads especially if it seems too good to be true.  Don’t allow yourself to fall in love with any specific exercise, training philosophy or technique.  Use common sense and what works.  Know when and why you are using anything.  In a nutshell: Be Functional!!!



Cook, Gray with Lee Burton, Kyle Kiesel, Greg Rose and Milo Bryant. Movement.   Functional Movement Systems: Screening, Assessment and Corrective Strategies.  Santa Cruz, California: On Target Publications, February 2013. Kindle.

Boyle, Michael. Advances in Functional Training: Training techniques for Coaches, Personal Trainers and Athletes.  Santa Cruz, California: On Target Publications, December 2011. Kindle.

Clark, Michael A., Scott C. Lucett and Brian G. Sutton. National Academy of Sports Medicine Essentials of Personal Fitness Training. Baltimore: Lippincot Williams & Wilkins, 2012. Print.

Norkin, Cynthia and Pamela Levangie. Joint Structure and Function: A Comprehensive Analysis. Philadelphia: F.A. Davis Company, 1983. Print.

Emery CA, Cassidy JD, Klassen TP, Rosychuk RJ and Rowe BH. Effectiveness of a home based balance training program in reducing sports-related injuries amongst healthy adolescents: a cluster randomized controlled trial. Can Med Assoc J 2005;172(6):749-54.