Revisiting The Single Visit Protocol For Determining The Electromyographic Fatigue Threshold

• Published in: Journal of strength and conditioning research 2017-12, Vol.31 (12), p.3503-3507
• Main Authors: Khan, Fatin L, Lawal, Jordan M, Kapture, Drew O, Swingle, Joseph D, Malek, Moh H
• Format: Article
• Language: English
• Subjects: Adolescent; Electromyography; Ergometry - methods; Exercise; Exercise - physiology; Exercise Test - methods; Fatigue - physiopathology; Humans; Male; Men; Muscle fatigue; Muscle Fatigue - physiology; Physical therapy; Quadriceps Muscle - physiology; Young Adult
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/JSC.0000000000002274

ABSTRACTThe electromyographic fatigue threshold (EMGFT) has been shown to demarcate between non-fatiguing and fatiguing exercise workloads. One potential limitation of incorporating the single EMGFT test in a clinical setting is the 2-min stage increment inherit to the protocol. In most rehabilitation clinics time with the client is limited and any testing procedures need to consider this factor. The purpose of this study, therefore, was to determine whether or not the estimation of the EMGFT is influenced by reducing the incremental stage to 1-min intervals. We hypothesized that 1-min incremental protocol would provide similar estimates of the EMGFT as the traditional 2-min incremental protocol. Nine college-aged men performed the single-leg knee-extensor ergometry at 1-min (3 Watts) and 2-min (6 Watts) stages in random order separated by 7 days. The exercise indices as well as EMGFT were determined from the two protocols and analyzed using a paired samples t-test. The EMG amplitude was assessed from the rectus femoris muscle. The results indicated significant differences between protocols for maximal power output (1-min31.7 ± 2.2 W vs. 2-min38.0 ± 3.3 W, p = 0.016) and heart rate at end-exercise (1-min137 ± 5 b/min vs. 2-min148 ± 5 b/min, p = 0.024). There was, however, no significant mean differences for EMGFT (1-min19.8 ± 1.8 vs. 2-min20.3 ± 1.9 W, p = 0.63) and rating of perceived exertion for the exercised leg (1-min9 ± 0 vs. 2-min9 ± 1, p = 0.68). These results indicate that reducing the exercise protocol by 50% did not change the estimated EMGFT. The practical application of this finding resides in the potential use in sports or rehabilitative settings in which there is limited time with the client and no objective measures of determine neuromuscular fatigue for aerobic exercise.