Premium
Muscle Recruitment Patterns Above Critical Power
Author(s) -
Alexander Andrew M,
Hammer Shane M,
Didier Kaylin D,
Baumfalk Dryden R,
Barstow Thomas J
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.710.2
Subject(s) - motor unit recruitment , electromyography , medicine , physical therapy , muscle fatigue , physical medicine and rehabilitation , muscle contraction , cycle ergometer , cardiology , heart rate , blood pressure
Critical power (CP) represents an exercise intensity that above which exercise tolerance is limited and can be predicted. As the muscle fatigues during constant‐load exercise above CP, muscle motor unit recruitment is increased to meet the exercise demand. Our laboratory has shown that at task failure in small muscle mass handgrip exercise, muscle recruitment is not different across exercise intensities above CP. Purpose To test the hypotheses that 1) end‐exercise muscle recruitment is not intensity‐dependent during whole body exercises above CP, and 2) at exercise intensities above CP muscle recruitment does not reach steady state, but continuously increases until task failure occurs. Methods To date, four healthy, young men (23.5 ± 2.0 yrs; 92.6 ± 4.2 kg, 175 ± 4 cm) completed five exercise bouts to task failure on separate days. During the first session, subjects performed an incremental test on a cycle ergometer to determine peak power (P peak ). The subjects then performed four constant load cycle tests on subsequent days. The power outputs during the constant load tests were selected to elicit task failure within the pre‐determined time range of 2–15 min to ensure all tests were above CP. Electromyography (EMG) was measured on the L vastus lateralis to quantify potential increases in muscle recruitment and were reported as 20 contraction averages. Results Average P peak was 300 ± 31 W. Work rate at which CP occurred was 178 ± 17W (59.4% ± 2.3 % P peak ). There were no significant differences in end‐exercise iEMG (p=0.078) among exercise intensities above CP. Further, for each exercise intensity all subjects demonstrated a progressive increase in iEMG until task failure. Conclusions Confirming our hypotheses, the current data suggest that during cycling exercise above CP, muscle recruitment at task failure is similar across exercise intensities.