Author(s): LI, T.E., HSU, W.1, LIN, Y.2, WEI, H.1, Institution: NATIONAL TAIWAN UNIVERSITY OF SCIENCE AND TECHNOLOGY, Country: TAIWAN, Abstract-ID: 1333

INTRODUCTION:
The Hamstrings to Quadriceps (H:Q) ratio is a crucial index utilized in sports science, rehabilitation, and athletic performance enhancement programs. It serves as a indicator of assessing muscle strength and functional muscle balance around the knee joint [1]. This study aimed to explore gender and fatigue effects on the H:Q ratio calculated by using both joint torque and muscle activation variables obtained from maximal isometric contractions and to investigate the correlation between the H:Q ratio calculated from the two different measuring instruments.
METHODS:
Twelve males and ten females triathletes who underwent pre- and post- isometric test before and after a incremental cycling test as fatigue protocol. The tests included three sets of maximal isometric contractions of knee extension and flexion at 90 degrees to the ground on their dominant side. Recordings of electromyography (EMG) signals from the vastus lateralis and semitendinosus muscles were conducted simultaneously. Peak torque and EMG signals were normalized to body weight and maximal voluntary contraction respectively before processed to calculate the H:Q ratios. Two-way ANOVA was employed to analyze fatigue and gender effects on peak torque at the knee joint and normalized integrated EMG as well as H:Q ratio obtained from these two measurement, namely the H:Q torque ratio and the H:Q EMG muscle activation ratio. Spearman correlation test was utilized to assess the correlation between H:Q torque ratio and H:Q EMG muscle activation ratio.
RESULTS:
Before and after fatigue protocol, a decreasing trend in peak torque values during knee joint extension and flexion was observed with significant differences noted. This led to no significant difference in the H:Q torque ratio (Male: PRE: 39.77±8.30, POST: 43.85±9.50%, Female: PRE: 43.42±10.38, POST: 43.79±11.61%; p=0.39) . Consequently, the H:Q EMG muscle activation ratio (Male: PRE: 45.48±18.84, POST: 41.16±17.52%, Female: PRE: 49.21±13.73, POST: 38.90±9.21%; p=0.02*) showed significant differences before and after fatigue. Additionally, no significant differences were found between genders, and there was no significant correlation between H:Q torque ratio and H:Q EMG muscle activation ratio, which is consistent with previous studies [2, 3].
CONCLUSION:
In our triathletes, both H:Q torque ratio and H:Q EMG muscle activation ratio fall around 40-50%. This wide range of H:Q torque ratio was possibly due to diverse in muscle demands due to age and level of triathlon. Different measuring instruments, where torque assesses muscle strength while EMG reveals muscle activation levels, affected H:Q ratio, adding another evidence in the literature that interpretation of the H:Q should be made with caution.
REFERENCES:
1.Ruas, C.V., et al., Sports medicine-open, 2019
2.Kong, P.W. and S.F. Burns, Phys Ther Sport, 2010
3.Oliveira, A.d.S.C., et al., J Electromyogr Kinesiol, 2009
Acknowledgments
Funding: Thanks to the support from the National Science and Technology Council (Guarding the infinite blooming power and beauty (2/4), Project No. 113-2425-H-011-001)