Author(s): WASHIF, J., Institution: NATIONAL SPORTS INSTITUTE OF MALAYSIA, Country: MALAYSIA, Abstract-ID: 324

INTRODUCTION:
Hamstring strength contributes to sprint performance by supporting horizontal force generation and accommodating the substantial eccentric demands associated with high-velocity running, including decelerating the knee joint. This study investigated the relationships between Nordic hamstring exercise (NHE) strength and performance outcomes across discrete sprinting phases.
METHODS:
Sixteen national- and international-level sprinters (8 male, 8 female; 21.8 ± 2.9 y; 1.68 ± 0.09 m; 61.1 ± 10.7 kg) completed maximal bilateral NHE tests using the NordBord device to determine peak absolute (N) and relative (N·kg⁻¹) strength (left, right, average). A 60-m sprint test (from a block start) was conducted two days later. Split times for each 10-m segment were obtained using electronic timing gates. Independent t-tests with Hedges’ g effect sizes compared male and female hamstring strength, and Pearson product–moment correlations examined associations between absolute and relative NHE strength and sprint times across each split, segment, and overall performance.
RESULTS:
Absolute hamstring strength was higher (p < 0.05) in males compared to females for the average leg (256 ± 43 N vs. 189 ± 34 N; Hedges’ g = 1.65), left leg (252 ± 51 N vs. 193 ± 47 N; g = 1.18), and right leg (260 ± 36 N vs. 185 ± 25 N; g = 2.05), with large to very large sex differences. Large to very large negative associations were found between absolute hamstring strength and sprint times from 20-m onwards (r = −0.54 to −0.72, p < 0.05). The strongest associations were observed for right-leg and average strength beyond 30-m (r = −0.65 to −0.72) and with maximum speed (r = −0.70 and −0.67, respectively). Relative strength showed weaker correlations (r = −0.28 to −0.34). Correlations with early acceleration (0–10m) were weakest (r < −0.40, p > 0.05).
CONCLUSION:
Absolute NHE strength demonstrated stronger associations with mid- and late-phase acceleration and maximal velocity than with early acceleration. This indicates that eccentric hamstring strength becomes increasingly important as sprinting speed rises, particularly from ~20 m onwards. As sprinting is a maximal-effort, high-velocity task that exposes the hamstrings to substantial mechanical loads, incorporating eccentric hamstring exercises such as the NHE may help enhance hamstring function and support improvements in mid- and late-acceleration and maximal-velocity performance. In contrast, early acceleration likely involves ‘lower hamstring loading’ and relies more on horizontal force production, glute–quadriceps concentric strength, and effective starting mechanics.