Effect of daily 3‐s maximum voluntary isometric, concentric, or eccentric contraction on elbow flexor strength

Abstract

The present study compared a 3‐s isometric maximal voluntary contraction (MVC), concentric MVC and eccentric MVC of the elbow flexors performed daily for 5 days a week for 4 weeks for changes in muscle strength and thickness. Young sedentary individuals were assigned to one of three training groups (n = 13 per group) that performed either 3‐s isometric, concentric, or eccentric MVC once a day for 20 days, or to a control group (n = 10) that had measurements without training. The participants in the isometric group performed isometric MVC at 55° (0.96 rad) elbow flexion, and those in the concentric or eccentric group performed concentric MVC or eccentric MVC between 10° (0.17 rad) and 100° (1.75 rad) elbow flexion at 30°/s (0.52 rad/s) on an isokinetic dynamometer. MVC isometric torque at 20° (0.35 rad), 55° (0.96 rad), and 90° (1.57 rad) elbow flexion, MVC concentric and eccentric torque at 30°/s (0.52 rad/s) and 180°/s (3.14 rad/s), and muscle thickness (MT) of biceps brachii and brachialis were measured before and several days after the 20th exercise session. The control group did not show any changes. The eccentric group showed increases (p < 0.01) in isometric (three angle average: 10.2 ± 6.4%), concentric (two velocity average: 12.8 ± 9.6%), and eccentric MVC torque (12.2 ± 7.8%). An increase (p < 0.05) was limited for isometric MVC torque (6.3 ± 6.0%) in the concentric group, and for eccentric MVC torque (7.2 ± 4.4%) in the isometric group. No significant changes in MT were evident for all groups. Performing one 3‐s MVC a day increased muscle strength, but eccentric MVC produced more potent effects than isometric or concentric MVC.

Greater effects by performing a small number of eccentric contractions daily than a larger number of them once a week

“…The sample size was estimated from our previous study 4 showing 12% increase in maximal voluntary eccentric contraction (MVC‐ECC) torque of the elbow flexors after performing a single three‐second maximal eccentric contraction a day for 5 days a week for 4 weeks. Since we had not known a possible difference between the groups, we used an effect size based on the above to estimate the number of samples for a group to be enough for detecting a possible increase in MVC‐ECC torque after training.…”

“…The dependent variables consisted of maximal voluntary isometric contraction (MVC‐ISO) torque at three different elbow joint angles (20°, 55°, 90°), concentric (MVC‐CON), and eccentric contraction (MVC‐ECC) torque at two angular velocities (30°/s, 180°/s), and biceps brachii and brachialis muscle thickness. Several MVC measurements were taken in accordance with our previous study 4 to examine whether any specifity of the training would be observed for other measurements than MVC‐ECC torque. These measurements were taken from the trained arm only, thus we did not investigate the cross‐education effect in the present study.…”

“…According to the previous study, 4 the MVC torque was measured at 20° (MVC‐ISO 20 ), 55° (MVC‐ISO 55 ), and 90° (MVC‐ISO 90 ) of elbow flexion in the same setting as that of the training using the isokinetic dynamometer. The MVC‐ISO torque measurements for each angle were performed in random order.…”

“…Regarding the muscle contraction type, previous studies have shown that resistance training focusing on eccentric (lengthening) muscle contractions (actions) is more effective than that focusing on concentric (shortening) muscle contractions (actions) for increasing muscle strength and muscle size 2,3 . We have recently reported that one 3‐second maximal eccentric contraction performed daily for 5 days a week (Monday–Friday) for 4 weeks increased maximum voluntary isometric (10.2 ± 6.4%), concentric (12.8 ± 9.6%), and eccentric contraction torque (12.2 ± 7.8%) of the elbow flexors without significant changes in muscle thickness of biceps brachii and brachialis 4 . It is interesting that only a small number of eccentric contractions (20 contractions in 4 weeks) can still increase muscle strength, but it is not known whether a larger number of eccentric contractions per session or in a week produce greater effects on muscle strength and muscle hypertrophy.…”

“…To increase the stimulus to the muscle in resistance exercise training, the number of contractions, the number of training sessions per week (frequency), or both can be increased. Since our previous study 4 showed that one 3‐second maximal eccentric contraction daily for 5 days a week was effective for increasing muscle strength, it is interesting to examine if a similar number of contractions performed in 1 day a week can still increase muscle strength in a similar magnitude. Grgic et al 5 showed in their meta‐analysis study that increasing the frequency of training could increase muscle strength and muscle size greater.…”