Reliability of Near-Infrared Spectroscopy for Measuring Intermittent Handgrip Contractions in Sport Climbers

Abstract

Baláš, J, Kodejška, J, Krupková, D, Hannsmann, J, and Fryer, S. Reliability of near-infrared spectroscopy for measuring intermittent handgrip contractions in sport climbers. J Strength Cond Res 32(2): 494-501, 2018-The use of near-infrared spectroscopy (NIRS) to investigate muscle oxygenation changes during physical tasks such as rock climbing has rapidly increased within recent years; yet, there is no known measure of reliability. The current study aimed to determine intersession reliability and minimal detectable change (MDC) of continuous wave NIRS parameters during intermittent handgrip contractions in rock climbers. Thirty-two sport climbers were tested for exhaustive intermittent handgrip exercise (8-second contraction-2-second relief) at 60% of maximal voluntary contraction on 3 separate days. During each visit, continuous wave NIRS was used to determine tissue saturation index (TSI) as the measure of tissue oxygenation in the flexor digitorum profundus. To assess the intersession reliability, the intraclass correlation coefficient (ICC), SEM, coefficient of variation (CV), and MDC were used. Mean deoxygenation during the contractions provided reliable results ([INCREMENT] TSI; first trial -8.9 ± 2.9%, second trial -8.8 ± 2.7%, and third trial -8.4 ± 2.6%; ICC = 0.692; SEM = 1.5%; CV = 17.2%; MDC = 4.2%). Mean muscle reoxygenation during the relief periods was similarly reliable ([INCREMENT] TSI; first trial 9.0 ± 3.1%, second trial 8.8 ± 2.9%, and third trial 8.5 ± 2.7%; ICC = 0.672; SEM = 1.7%; CV = 19.0%, MDC = 4.7%). As such, continuous wave NIRS provides a reliable measure of deoxygenation and reoxygenation during intermittent contractions to failure in the forearm flexors of rock climbers. Differences exceeding ∼4.5% for [INCREMENT] TSI during contraction and relief periods should be considered meaningful.

Males benefit more from cold water immersion during repeated handgrip contractions than females despite similar oxygen kinetics

“…Differences in the haemodynamic response between the 1st and 2nd recovery show that muscle temperature, rather than hydrostatic pressure, are responsible for TSI changes. However, the differences in tHb and TSI between PAS and CWI recovery strategies were small and did not exceed the minimal detectable changes stated for this type of measurement [1].…”

“…Effect size for ANOVA was calculated using partial eta squared (µ p 2 ). Mean detectable change, as stated previously [1], was taken for a criterion of practical effect. All calculations were completed using IBM SPPS 24.0 (IBM, Armonk, New York).…”

Muscle oxygen dynamics in elite climbers during finger-hang tests at varying intensities

“…For this reason, a plethora of studies have demonstrated the diagnostic qualities of NIRS, from threshold testing 34,35 , muscle damage analysis 36 and high intensity interval response 37,38 . Similar physiological reasoning has been applied to NIRS measurements during sport climbing, highlighting the importance of specific NIRS derived parameters 17 . SmO 2 min as an indicator of muscle oxidative capacity and a predictor of performance for climbing specifically is discussed by both Balas et al 12 and Fryer et al 13 .…”

“…The hand position applied by all participants was a half crimp; the thumb was not used. A 23 mm rung depth was used for all the trails, following the procedure of a series of previous publication 17,24 . For every trial the participants were allowed to apply commercially available climbing chalk (magnesium carbonate).…”

“…A greater local oxidative capacity has shown to enhance sport specific strength and endurance when comparing novice and expert climbers 13 , with a considerable degree of predictive power to determine climbing level; linear regression model predicting Red-point grade (IRCRA Scale) from tissue oxygen resaturation rate: y = −0.351 + 14.121, R 2 = 0.24 13 . Numerous studies look both at isometric holds and repeated or intermittent isometric holding as performance limiting components and their effect on NIRS dynamics 12,15,17 . Specifically, sustained isometric holds on static gripping tasks have shown to result in NIRS dynamics that indicate loss of force production 16 .…”