Endurance capacity of untrained males and females in isometric and dynamic muscular contractions

Summary The capacity to perform isometric and dynamic muscle contractions at different forces has been measured in two separate groups of subjects: 25 men and 25 women performed sustained isometric contractions of the knee-extensor muscles of their stronger leg to fatigue, at forces corresponding to 80%, 50% and 20% of the maximum voluntary force of contraction (MVC). The second experimental model involved a bilateral elbowflexion weight lifting exercise. Eleven women and 12 men performed repetitions at loads corresponding to 90%, 80%, 70%, 60% and 50% of maximum load (lRM), at a rate of 10 · min^–1 to the point of fatigue. Males were stronger (p<0.001) than females in both the static (675±120 N vs 458±80 N; mean±SD) and dynamic (409±90 N vs 190±33 N) contractions. Isometric endurance time of the males at a force corresponding to 20% of MVC was less than that of the females (180±51 s vs 252±56 s; p<0.001) but there was no difference between the sexes at 50% or 80% of MVC. Similarly, when the sexes were compared using dynamic elbow-flexion exercise, the female subjects were able to perform a greater number of repetitions than males at loads of 50% (p<0.005), 60% (p<0.001) and 70% (p<0.025) of lRM, but there was no difference between the sexes at loads of 80% or 90% of lRM. The results suggest that the endurance capacity of women is greater than that of men in both isometric and dynamic muscular exercise when the work load is relatively low compared with maximum; at higher forces, there is no difference between the sexes in endurance performance.