Kettelbell swing
targets semitendinosus and supine leg curl targets biceps femoris: an EMG study
with rehabilitation implications.

Zebis MK, Skotte J,
Andersen CH, Mortensen P, Petersen MH, Viskaer TC, Jensen TL, Benecke J and
Andersen LL. Br J Sports Med. 2012; [Eup Ahead of Print].

With knee injuries,
such as anterior cruciate ligament ruptures, being increasingly seen in sports,
more and more emphasis has been placed on prophylactic exercises to reduce the risk
of injury. Unfortunately, little is known about how different exercises
challenge the hamstring muscles, which may be a key muscle group to optimize in
prophylactic or rehabilitation programs. Therefore, Zebis and colleagues
evaluated the levels of medial and lateral hamstring activation during selected
exercises that are commonly used in rehabilitation and prophylactic exercise
programs. They selected elite female handball (n=8) and soccer players (n=8) with no previous hamstring or knee injuries. Prior to testing, all participants underwent a familiarization session where they performed 3 maximum voluntary isometric hamstring muscle contractions (MVC) on a Biodex isokinetic dynamometer. The highest of the 3 MVC values was used as a reference for the exercises. Surface electromyography was performed by placing electrodes on the skin over the biceps femoris and semitendinosus muscles. The exercise protocols were divided into 9 strength and 5 balance exercises. Balance exercises consisted of one-leg jump onto balance mat, one-leg landing from box on balance mat, one-leg drop jump on balance mat, one-leg forward jump, and one-leg side jump. Strength exercises were two-hand
kettlebell swing
, Nordic
hamstring lowers
, supine pelvis lifts, Romanian deadlift,
hyperextensions off table, hyperextensions off table with barbell, seated leg
curls, prone leg curl, and supine one-leg curls. All exercises were performed
by the participants in a random order with a 3 minute rest period between exercises
to avoid fatigue. The overall results are reported in the table below.

Exercises Targeting
Biceps Femoris
Exercises Targeting
1 = least muscle
activity (from the top 10)
1. one-leg drop
jump on balance
1. one-leg jump
onto balance mat
2. one-leg jump
onto balance mat
2. hyperextensions
off table
3. supine pelvis
3. Romanian
4. hyperextensions
off table
4. supine pelvis
5. Nordic hamstring
5. Nordic hamstring
6. prone leg curl,
6. prone leg curl
7. kettlebell swing
7. seated leg curls
8. hyperextensions
off table with barbell
8. hyperextensions
off table with barbell
9. seated leg curls
9. supine one-leg
10. supine one-leg
10. kettlebell
10 = most muscle

Overall, this study
provides and interesting look at how effective various exercises are at
activating different hamstring muscles. Clinically, these data can help
clinicians choose the exercises to target the hamstrings group and specific
muscles leading to more beneficial strength gains but their efficacy in aiding
prevention programs is less clear. Exercises used in this study were not sport
specific, a potentially vital element in any injury prevention program.
Therefore, one must assume that while these exercises are beneficial to use in
an injury prevention program, the clinician must make an effort to implement
sport-specific exercises as well. Furthermore, a note of caution must be made
regarding incorrectly performed trials. The authors mentioned that if a
participant performed a trial incorrectly, that trial was disqualified and a
new trial was performed; however, no mention was made to if this occurred and
if so, how often. One could surmise that adding more trials could increase the
participant’s fatigue. Tell us what you think about the exercises you choose
for your patients. What criterion goes into choosing the exercises you use? Do
you find that the exercises you typically choose are more or less effective
according to the data in this study?

Written by: Kyle
Reviewed by: Jeffrey

Related Posts:

Zebis MK, Skotte J, Andersen CH, Mortensen P, Petersen MH, Viskær TC, Jensen TL, Bencke J, & Andersen LL (2012). Kettlebell swing targets semitendinosus and supine leg curl targets biceps femoris: an EMG study with rehabilitation implications. British Journal of Sports Medicine PMID: 22736206