Squats and Deadlifts

Squats

 

Squat Variations

Front squat, hack squat, DB/KB/sand-bag squat, DB squat with shoulders flexed parallel to the ground/Smith machine squat, split stance squat, box/bench squat, squat with chains or bands, pause squat, single-leg squat (floor/BOSU), Front foot elevated single leg squat, Rear foot elevated single-leg squat(Bulgarian split squat), TRX single-leg squat, Zercher squat, weighted vest squat, rack squat, safety squat, SB wall squats, ISOM wall squats, squats with resistance band at knees, BW squats, TRX body weight squats, MB squats, knee squats, buddy squats, keg squat, BOSU squat, Sumo squat, BW/DB/KB duck walks, KB swing squat, jump squat (with various resistance)

 

Foot Position during the squat

Some athletes perform a variety of stance widths to vary muscle activation or add variety to a training programme. In a study by Esamilla et al (2001a), a wider (~169% of shoulder width) stance produced 7-12 deg greater horizontal thigh position, 6-11 deg greater hip flexion, 6 degrees greater hip external rotation and 5-9 deg greater vertical lower leg position.

 

Knee Issues

During the squat the knee is required to move through a range of motion of between 0 and 160 degrees. Many studies have examined the forces that are present within the knee and in one (Nagura et al, 2002) it was shown that in a group of powerlifters the maximal force exerted through the patellar tendon during a deep squat was at 130 degrees of knee flexion and when lifting 2.5 times bodyweight. This peak force was found to be 6000N although it has also been shown elsewhere that the patellar tendon is capable of tensile forces of between 10 000 and 15 000 N.

Posterior-Anterior positioning
A common teaching point for beginners is to recommend keeping the knee behind the line of the toes on the same leg. Whilst sitting back into a squat encourages recruitment of the gluteal muscles, exercises that allow the knee to travel forwards are not going to cause damage if used as part of a range of exercises for athletes with healthy knees. They can, in fact, play a positive role in increasing mobility of the ankle and hip joint in exercises such as a lunge. For more click here
 
Squat Depth
Squat depth is important when trying to develop strength full the full range of movement. The Gluteus Maximus does not demonstrate significantly different recruitment patterns when performing partial or parallel squat depths but does see a significant increase in its force production during full depth squats (Caterisano et al, 2002)

Ankle Issues
It has been shown that those with reduced range of motion at the ankle joint have a higher predisposition to medial knee displacement. If this results in dynamic knee valgus alignment and then occurs with an internal tibial rotation it creates the optimal environment for an ACL injury.
 
The tuck under (butt-winking)
Tony Gentilcore articles on cause and correction [part 1][part 2]
 
Further Links
Dan John teaching squat depth - [youtube]
Mike Robertson article on squat technique and corrections [website]

The Deadlift 
Muscle activation in conventional and sumo deadlifts [click here]
Gentilcore, T (2013) Deadlifts: From suck to sick [available at www.t-nation.com] [click here]

Swinton, P. A., Stewart, A. D., Keogh, J. W., Agouris, I., & Lloyd, R. (2011). Kinematic and kinetic analysis of maximal velocity deadlifts performed with and without the inclusion of chain resistance. The Journal of Strength & Conditioning Research, 25(11), 3163-3174.[abstract]

References & Further Reading
Bell, D. R., Padua, D. A., & Clark, M. A. (2008). Muscle strength and flexibility characteristics of people displaying excessive medial knee displacement. Archives of physical medicine and rehabilitation, 89(7), 1323-1328 [full text]

Bird, S. P., & Casey, S. (2012). Exploring the front squat. Strength & Conditioning Journal, 34(2), 27-33 [abstract]

BIrd, S., & Barrington-Higgs, B. (2010). Exploring the deadlift. Strength & Conditioning Journal, 32(2), 46-51[abstract]

Caterisano, A., Moss, R. F., Pellinger, T. K., Woodruff, K., Lewis, V. C., Booth, W. and Khadra, T. (2002) The effect of back squat depth on the EMG activity of 4 superficial hip and thigh muscles. Journal of Strength and Conditioning Research. Vol. 16, No. 3: 428–432. [Online]. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12173958. [full text]

Comfort, P., & Kasim, P. (2007). Optimizing squat technique. Strength & Conditioning Journal, 29(6), 10-13. [full text]

Clark, D. R., Lambert, M. I., & Hunter, A. M. (2012). Muscle activation in the loaded free barbell squat: A brief review. The Journal of Strength & Conditioning Research, 26(4), 1169-1178 [full text]

Gullett, J. C., Tillman, M. D., Gutierrez, G. M., & Chow, J. W. (2008). A biomechanical comparison of back and front squats in healthy trained individuals. The Journal of Strength & Conditioning Research, 23(1), 284-292.[full text]

Escamilla, R.F., Fleisig, G.S., Lowry, T.M., Barrentine, S.W. and Andrews, J.R. (2001a) A three-dimensional biomechanical analysis of the squat during varying stance widths. Med. Sci. Sports Exerc., Vol. 33, No. 6, pp. 984–998 [full text]
 
Escamilla, R., Fleisig, G., Zheng, N., Lander, J., Barrentine, S., Andrews, J., Bergemann, B., and Moorman, C. (2001) Effects of technique variations on knee biomechanics during the squat and leg press. Med Sci Sports Exerc. Vol.33, No.9, 1552-1566 [full text]
 
Escamilla, R., Zheng, N., Macleod, T., Imamura, R., Edwards, W., Hreljac, A., Fleisig, G., Wilk, K., Moorman,C., Paulos, L., and Andrews, J. (2010) Cruciate ligament forces between a short and a long step forward lunge. Med Sci Sports Exerc. Vol.42, No.10, 1932-1942 [abstract]
 
Fry AC, Smith JC, Schilling BK. (2003) Effect of knee position on hip and knee torques during the barbell squat. J Strength Cond Res. Nov;17(4):629-33.[html full text]

Gullett, J. C., Tillman, M. D., Gutierrez, G. M. and Chow, J. W. (2008) A Biomechanical Comparison of Back and Front Squats in Healthy Trained Individuals. Journal of Strength & Conditioning Research. Vol. 23, No. 1: 284–292. [fulltext]

McKean, M. R., Dunn, P. K., & Burkett, B. J. (2010). The lumbar and sacrum movement pattern during the back squat exercise. The Journal of Strength & Conditioning Research, 24(10), 2731-2741 [researchgate]

Nagura, T., Dyrby, C. O., Alexander, E. J., & Andriacchi, T. P. (2002). Mechanical loads at the knee joint during deep flexion. Journal of Orthopaedic Research, 20, 881-886 [full text]

Schellenberg, F., Lindorfer, J., List, R., Taylor, W. R., & Lorenzetti, S. (2013). Kinetic and kinematic differences between deadlifts and goodmornings. BMC sports science, medicine and rehabilitation, 5(1), 27.[full text]

Schuna Jr, J. M., & Christensen, B. K. (2010). The Jump Squat: Free Weight Barbell, Smith Machine, or Dumbbells?. Strength & Conditioning Journal, 32(6), 38-41

Shoenfeld, B. J. (2010) Squatting Kinematics and Kinetics and their Application to Exercise Performance. Journal of Strength and Conditioning Research. Vol. 24, No. 12: 3497–3506. [full text]

Swinton, P. A., Stewart, A., Agouris, I., Keogh, J. W., & Lloyd, R. (2011). A biomechanical analysis of straight and hexagonal barbell deadlifts using submaximal loads. The Journal of Strength & Conditioning Research, 25(7), 2000-2009. [abstract]

Winwood, P. W., Hume, P. A., Cronin, J. B., & Keogh, J. W. (2014). Retrospective injury epidemiology of strongman athletes. The Journal of Strength & Conditioning Research, 28(1), 28-42.[abstract]