Electrical stimulation is an established method that is used to improve muscle strength. The present study compared changes in the navicular drop test (NDT), muscle size, the five times sit to stand (5TSTS) test, the timed up and go (TUG) test, and the risk of falls in response to transcutaneous electrical nerve stimulation (TENS) plus short foot exercise (SFE) and SFE alone in 68 healthy elderly participants aged 65–75 years. Participants were randomly assigned to two groups: TENS plus SFE and SFE alone (with sham TENS). Measurements of NDT, muscle size, 5TSTS, TUG, and risk of falls were made before and after 4 weeks of training. The NDT was significantly improved by a median of 0.31 mm in the TENS plus SFE group and 0.64 mm in the SFE alone group (p < 0.001). Similarly, there was a significant improvement in Falls Efficacy Scale International (FES-I), 5TSTS, and TUG for both groups (p < 0.001). The abductor hallucis muscle size increased by 0.23 cm2 in the TENS plus SFE group and 0.26 cm2 in the SFE alone group (p < 0.001). There were no significant differences between the two groups for any variables (p > 0.05) except TUG, which showed a greater improvement in the TENS plus SFE group (p = 0.008). Our findings demonstrated that TENS plus SFE and SFE alone improved intrinsic foot muscle size. However, TENS plus SFE tended to improve NDT more than SFE alone, particularly in cases of severe muscle weakness. Thus, the combined use of TENS plus SFE could be recommended for muscle strengthening and balance programs for fall prevention in older adults.
New Findings: What is the central question of this study? Why do some subjects recover slowly following a bout of eccentric exercise and why is recovery faster following a repeated bout? What is the main finding and its importance? The results are consistent with two major causes of the reduction of quadriceps torque, the onset of low‐frequency fatigue which recovered relatively fast and a second, delayed form of damage. Differences in the delayed damage process largely accounted for the differences in the rate of torque recovery between subjects after a first bout and it was suppression of the delayed damage which accounted for the faster recovery following a repeated bout of eccentric exercise. The purpose of this study was to determine the extent to which low‐frequency fatigue (LFF) accounts for the loss of quadriceps strength and time course of recovery following a series of drop jumps (DJs). Seventeen female subjects (20.8 ± 1.4 years) undertook 100 DJs, which were repeated 4 weeks later. Maximum isometric torque (MIT) and the ratio of torque generated by 20 and 100 Hz electrical stimulation (20/100), as a measure of LFF, were measured over 7 days following each series of DJs. After the first series the 20/100 ratio fell to a greater extent than MIT (to 35 ± 8.7% and 69 ± 11%, respectively) but recovered over 2–3 days, while MIT showed little recovery over this time. Changes of the 20/100 ratio were similar between subjects with fast or slow MIT recovery. Following the second series of DJs, changes in the 20/100 ratio were similar to those of the first bout and there were no differences between fast and slow recovering subjects. MIT, however, recovered more rapidly than after the first bout; the faster recovery was confined to the subjects who recovered slowly following the first bout. The results are consistent with two major causes of the reduction of quadriceps torque, the onset of low‐frequency fatigue which recovered relatively fast and a second, delayed, form of damage. The latter largely accounted for the differences in MIT recovery between subjects after the first bout, while suppression of the delayed damage accounted for the faster recovery following the repeated bout.