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Effects of Eccentric Exercise‐Induced Muscle Damage on Endothelial Function and Skeletal Muscle Microvascular Deoxygenation
Author(s) -
Caldwell Jacob Troy,
Ade Carl J,
Black Christopher D,
Wardlow Garrett C,
Maggard Sierra F,
Branch Patrece A,
Hardy Rachel N,
Quarshie Alwyn T
Publication year - 2016
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.30.1_supplement.763.28
Subject(s) - brachial artery , medicine , cardiology , eccentric , skeletal muscle , femoral artery , vo2 max , heart rate , blood pressure , physics , quantum mechanics
Unaccustomed eccentric exercise has been shown to result in muscle damage (EIMD) and to decrease maximal aerobic exercise capacity (VO 2max ). Central and peripheral cardiovascular function mediates VO 2 max , but it is unclear whether alterations in endothelial and skeletal muscle microvascular function play a role in the reduced VO 2 max seen after EIMD. We tested the hypotheses that EIMD of the knee extensors would: 1) decrease local (femoral artery) and systemic (brachial artery) endothelial‐dependent flow‐mediated dilation (FMD), 2) alter the near‐infrared spectroscopy (NIRS)‐derived muscle microvascular deoxygenation (Δ[HHb]) response during incremental cycling exercise, which reflects the balance between muscle O 2 delivery and O 2 utilization, and 3) decrease VO 2max . To date, five of a planned fifteen participants have completed a brachial and femoral artery FMD test, an index of endothelial‐dependent dilation, followed by an incremental exercise test to exhaustion on a cycle ergometer during which pulmonary VO 2 and changes in NIRS‐derived Δ[HHb] were measured. Δ[HHb] was measured in the m. vastus lateralis, was normalized to the total response, and was then expressed as a function of relative work rate and fit using a sigmoid function. Each test was performed prior to (Pre) and 48‐hr after a bout of knee extensor eccentric exercise designed to elicit localized muscle damage (Post). Pre brachial artery FMD was 9.7 ± 8.9% and Post brachial artery FMD was 3.6 ± 7.3% ( P = 0.1, Effect size (ES) = 0.3). Pre femoral artery FMD was 7.9 ± 7.4% compared to a Post FMD of 1.0 ± 4.4% ( P = 0.1, ES = 1.1). During exercise the sigmoid slope was 35.4 ± 25.6 %/% Pre and 37.9 ± 22.1 %/% Post ( P = 0.8, ES = .1) Similarly, the c/d value (i.e., 50% of the amplitude of the Δ[HHb] response was 46.7 ± 102.0 % Pre compared to 36.6 ± 46.7 % Post ( P = 0.7, ES = 0.1). Pre VO 2max was 3.3 ± 0.64 l·min −1 while Post VO 2max was 3.1 ± 0.76 l·min −1 ( P = 0.1, ES = 0.3). To date this study is under powered (0.08) and additional participants will be tested and included in the final analysis. The findings from this study will provide insight into macro‐ and microvascular function following EIMD and their association with changes in VO 2max .