Unilateral Contributions to Bilateral Eccentric Hamstring Exercise - A Preliminary Case Series Analysis
Location
Poster Session 2 (Henderson Library)
Session Format
Poster Presentation
Your Campus
Statesboro Campus- Henderson Library, April 20th
Academic Unit
Department of Health and Kinesiology
Research Area Topic:
Exercise Science & Human Performance - Exercise Science
Co-Presenters and Faculty Mentors or Advisors
Dr. Nicholas Siekirk, Jacob Smith
Abstract
Recent evidence has questioned the utility of eccentric (ECC) exercise in the prevention of hamstring (HS) strains. Inter-leg recruitment strategies influence the intervention’s success PURPOSE: To examine whether bilateral eccentric exercises display asymmetric recruitment strategies METHODS: Prior to maximum voluntary contractions (MVC), ten trained college-aged participants performed dynamic mobility drills. Isometric dynamometry measured participant’s peak torque (pTorq) for the gluteus maximus (Gmax) and medial gastrocnemius (MG) in prone. The pTorq was obtained for the knee in seated posture with isokinetic dynamometry set at 60 o /sec and 120 o /sec to measure concentric (CON) and ECC pTorq of the quadriceps (Q) and HS. Ipsilateral strength ratios (CON60 o Q/ECC120 o HS) were compared bilaterally with paired t-test. Surface electromyography (sEMG) during ECC exercise was bilaterally recorded from the MG, semitendinosus (ST), biceps femoris (BF) and GMax and was normalized to pTorq output during MVCs (%MVC). ECC exercise variations included (n = 3) reps of the Nordic Hamstring Exercise (NHSE), NHSE at 7 o decline (NHSE7 o ) and Razor Curl in randomized order. Separate 3-way (variation, rep, side) RMANOVAs were conducted on each muscle. RESULTS: Contralateral differences in strength ratios were not detected, MD = 0.06 ft-lbs; 95% CI: -0.31 to 0.18, d = 0.15. Data suggested an interaction between variation, rep, and side for the MG; F(1.75, 15.76) = 3.07, n 2 = 0.254. A large main effect of side was detected for Gmax; F(1, 9) = 11.58, n 2 = 0.563. The participant R Gmax (95% CI: 31.07% to 84.25%) had greater %MVC than L (95% CI: 20.98% to 57.45%), a MD = 18.44% (95% CI: 6.18% to 30.71%). A large main effect of exercise variation was detected for ST, F(1.17, 10.51) = 3.23, n 2 = 0.264 and BF, F(1.42, 12.78) = 4.48, n 2 = 0.332. The Razor curl mEMG was reduced in ST and BF vs. NHSE7 o ; ST [MD = -7.29% (95% CI: -13.00% to -1.58%)], BF [MD = -17.00% (95% CI: -30.57% to -3.42%)]. CONCLUSIONS: Data suggests recruitment strategies bias the R GMax across eccentric exercise variations. Furthermore, these findings support the pursuit of larger scaled investigations to examine recruitment strategies during eccentric HS exercise.
Program Description
We explored how the hamstring muscle group presents a unilateral bias during a bilateral exercise such as the nordic hamstring curl.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Presentation Type and Release Option
Presentation (Restricted to Georgia Southern)
Start Date
4-20-2022 1:30 PM
End Date
4-20-2022 3:00 PM
Recommended Citation
Smith, Jacob, "Unilateral Contributions to Bilateral Eccentric Hamstring Exercise - A Preliminary Case Series Analysis" (2022). GS4 Georgia Southern Student Scholars Symposium. 26.
https://digitalcommons.georgiasouthern.edu/research_symposium/2022/2022/26
Unilateral Contributions to Bilateral Eccentric Hamstring Exercise - A Preliminary Case Series Analysis
Poster Session 2 (Henderson Library)
Recent evidence has questioned the utility of eccentric (ECC) exercise in the prevention of hamstring (HS) strains. Inter-leg recruitment strategies influence the intervention’s success PURPOSE: To examine whether bilateral eccentric exercises display asymmetric recruitment strategies METHODS: Prior to maximum voluntary contractions (MVC), ten trained college-aged participants performed dynamic mobility drills. Isometric dynamometry measured participant’s peak torque (pTorq) for the gluteus maximus (Gmax) and medial gastrocnemius (MG) in prone. The pTorq was obtained for the knee in seated posture with isokinetic dynamometry set at 60 o /sec and 120 o /sec to measure concentric (CON) and ECC pTorq of the quadriceps (Q) and HS. Ipsilateral strength ratios (CON60 o Q/ECC120 o HS) were compared bilaterally with paired t-test. Surface electromyography (sEMG) during ECC exercise was bilaterally recorded from the MG, semitendinosus (ST), biceps femoris (BF) and GMax and was normalized to pTorq output during MVCs (%MVC). ECC exercise variations included (n = 3) reps of the Nordic Hamstring Exercise (NHSE), NHSE at 7 o decline (NHSE7 o ) and Razor Curl in randomized order. Separate 3-way (variation, rep, side) RMANOVAs were conducted on each muscle. RESULTS: Contralateral differences in strength ratios were not detected, MD = 0.06 ft-lbs; 95% CI: -0.31 to 0.18, d = 0.15. Data suggested an interaction between variation, rep, and side for the MG; F(1.75, 15.76) = 3.07, n 2 = 0.254. A large main effect of side was detected for Gmax; F(1, 9) = 11.58, n 2 = 0.563. The participant R Gmax (95% CI: 31.07% to 84.25%) had greater %MVC than L (95% CI: 20.98% to 57.45%), a MD = 18.44% (95% CI: 6.18% to 30.71%). A large main effect of exercise variation was detected for ST, F(1.17, 10.51) = 3.23, n 2 = 0.264 and BF, F(1.42, 12.78) = 4.48, n 2 = 0.332. The Razor curl mEMG was reduced in ST and BF vs. NHSE7 o ; ST [MD = -7.29% (95% CI: -13.00% to -1.58%)], BF [MD = -17.00% (95% CI: -30.57% to -3.42%)]. CONCLUSIONS: Data suggests recruitment strategies bias the R GMax across eccentric exercise variations. Furthermore, these findings support the pursuit of larger scaled investigations to examine recruitment strategies during eccentric HS exercise.
