Effects of induced local ischemia during a 4-km cycling time trial on neuromuscular fatigue development

Autor(es)

Azevedo, Rafael de Almeida ^[1] ; Cruz, Ramon ^[1] ; Hasegawa, Julio Satoshi ^[1] ; Gaspari, Arthur Fernandes ^[2] ; Traina Chacon-Mikahil, Mara Patricia ^[2] ; Silva-Cavalcante, Marcos David ^{[1, 3]} ; Coelho, Daniel Boari ^[4] ; Lima-Silva, Adriano E. ^{[3, 5]} ; Bertuzzi, Romulo ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Phys Educ & Sport, Endurance Performance Res Grp, Sao Paulo - Brazil

^[2] Univ Estadual Campinas, Sch Phys Educ, Lab Exercise Physiol, Campinas, SP - Brazil

^[3] Univ Fed Alagoas, Fac Nutr, Maceio, Alagoas - Brazil

^[4] Fed Univ ABC, Ctr Engn Modeling & Appl Social Sci, Sao Paulo - Brazil

^[5] Univ Tecnol Fed Parana, Human Performance Res Grp, Curitiba, Parana - Brazil

• Tipo de documento: Artigo Científico
• Fonte: AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY; v. 320, n. 6, p. R812-R823, JUN 2021.
• Citações Web of Science: 0

Resumo

The present study analyzed the effects of local ischemia during endurance exercise on neuromuscular fatigue (NMF). Nine cyclists performed, in a counterbalanced order, two separate 4-km cycling time trials (TT) with (ISCH) or without (CONTR) induced local ischemia. NMF was characterized by using isometric maximal voluntary contractions (IMVC), whereas central {[}voluntary activation (VA)] and peripheral fatigue {[}peak torque of potentiated twitch (TwPt)] of knee extensors were evaluated using electrically evoked contractions performed before (PRE) and 1 min after (POST) the TT. Electromyographic activity (EMG), power output (PO), oxygen uptake ((V)over dot(2)), and rating of perceived exertion (RPE) were also recorded. The decrease in IMVC (-15 +/- 9% vs. -10 +/- 8%, P = 0.66), VA (-4 +/- 3% vs. -3 +/- 3%, P = 0.46), and TwPt (-16 +/- 7% vs. -19 +/- 14%, P = 0.67) was similar in ISCH and CONTR. Endurance performance was drastically reduced in ISCH condition (512 +/- 29 s) compared with CONTR (386 +/- 17 s) (P < 0.001), which was accompanied by lower EMG, PO, and (V)over dot(2) responses (all P < 0.05). RPE was greater in ISCH compared with CONTR (P 0.05), but the rate of change was similar throughout the TT (8.19 +/- 2.59 vs. 7.81 +/- 2.01 RPE.% of total time -1, P> 0.05). These results indicate that similar end-exercise NMF levels were accompanied by impaired endurance performance in ISCH compared with CONTR. These novel findings suggest that the local reduced oxygen availability affected the afferent feedback signals to the central nervous system, ultimately increasing perceived effort and reducing muscle activity and exercise intensity to avoid surpassing a sensory tolerance limit before the finish line. (AU)

• Processo FAPESP: 17/22053-0 - Pacing no ciclismo: um estudo sobre a interface fadiga neuromuscular e perfil metabólico
• Beneficiário: Rômulo Cássio de Moraes Bertuzzi
• Modalidade de apoio: Auxílio à Pesquisa - Regular