In vivo assessment of muscle mitochondrial function in healthy, young males in relation to parameters of aerobic fitness

Abstract

Purpose The recovery of muscle oxygen consumption (m O 2 ) after exercise provides a measure of skeletal muscle mitochondrial capacity, as more and better-functioning mitochondria will be able to restore m O 2 faster to the pre-exercise state. The aim was to measure muscle mitochondrial capacity using near-infrared spectroscopy (NIRS) within a healthy, normally active population and relate this to parameters of aerobic fitness, investigating the applicability and relevance of using NIRS to assess muscle mitochondrial capacity non-invasively. Methods Mitochondrial capacity was analysed in the gastrocnemius and flexor digitorum superficialis (FDS) muscles of eight relatively high-aerobic fitness ( O 2 peak ≥ 57 mL/kg/min) and eight relatively low-aerobic fitness male subjects ( O 2 peak ≤ 47 mL/kg/min). Recovery of whole body O 2 , i.e. excess post-exercise oxygen consumption (EPOC) was analysed after a cycling protocol. Results Mitochondrial capacity, as analysed using NIRS, was significantly higher in high-fitness individuals compared to low-fitness individuals in the gastrocnemius, but not in the FDS ( p = 0.0036 and p = 0.20, respectively). Mitochondrial capacity in the gastrocnemius was significantly correlated with O 2 peak ( R 2 = 0.57, p = 0.0019). Whole body O 2 recovery was significantly faster in the high-fitness individuals ( p = 0.0048), and correlated significantly with mitochondrial capacity in the gastrocnemius ( R 2 = 0.34, p = 0.028). Conclusion NIRS measurements can be used to assess differences in mitochondrial muscle oxygen consumption within a relatively normal, healthy population. Furthermore, mitochondrial capacity correlated with parameters of aerobic fitness ( O 2 peak and EPOC), emphasising the physiological relevance of the NIRS measurements.

Improving biologic predictors of cycling endurance performance with near‐infrared spectroscopy derived measures of skeletal muscle respiration: E pluribus unum

“…NIRS‐derived measures of skeletal muscle oxygenation allow for the direct noninvasive assessment of maximal rates of skeletal muscle respiration (Hamaoka et al, ; Ryan et al, ; Ryan, Southern, Reynolds, et al, ), with a precision capable of differentiating skeletal muscle oxidative potential across human participants with differing levels of fitness (Brizendine, Ryan, Larson, & McCully, ; Lagerwaard et al, ) and within‐subject skeletal muscle respiratory changes contrasting trained and nontrained arms (Ryan, Southern, Brizendine, & McCully, ). NIRS‐derived measures of maximal skeletal muscle respiration have been validated against high‐resolution respirometry‐derived measures of maximal ADP‐stimulated state 3 respiration (Ryan et al, ) using an in situ mitochondrial model with permeabilized muscle sample preparations that leave the mitochondrial reticular network intact (Kuznetsov et al, ) and in vivo PCr recovery kinetics via 31 phosphorus‐magnetic resonance spectroscopy (Ryan, Brizendine, et al, ).…”

Near Infrared Spectroscopy Measurements of Mitochondrial Capacity Using Partial Recovery Curves

“…Typically, 18-26 ischemic occlusions are needed to accurately fit the metabolic rates to a mono-exponential curve approaching a steady baseline for a single rate constant to be generated (Sako et al, 2001;Motobe et al, 2004). As 2-3 trials are typically performed to obtain an accurate assessment of the recovery rate constant (Adami and Rossiter, 2018;Lagerwaard et al, 2019), 36-78 short cuff occlusions are required over 30-45 min (Willingham and McCully, 2017). This large number of cuffs can be difficult to tolerate, especially in at-risk and elderly populations.…”

New Insights into Mechanical, Metabolic and Muscle Oxygenation Signals During and After High-Intensity Tethered Running

“…NIRS is a non-invasive method that has been shown to be a significant tool capable of estimating the muscle oxygenation events, such as variations in oxyhemoglobin (O 2 Hb), deoxyhemoglobin (HHb), total hemoglobin (tHb) and tissue saturation index (TSI) in skeletal muscle 30,31 . This technique based on optical principles has been commonly used in clinical studies involving pathologies and exercise prescription 32,33 and recently focused on inactive participants 12 , active subjects 34,35 and athletes 16,[36][37][38] to improve the knowledge about physiological and performance responses. In a recent systematic review, Perrey and Ferrari 39 suggested that the popularity of muscle oxygenation studies in exercise increased after the commercialization of portable wireless muscle oximeters.…”