Ashley M. Goodwin 1-2 , Jacqueline Montes 2 , Ipek Ensari 3, Ashwini K. Rao 2 , Carol Ewing Garber FACSM 1
1-Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY
2-Department of Rehabilitation and Regenerative Medicine, Programs in Physical Therapy, Columbia University Irving Medical Center, New York, NY
3-Columbia University Data Science Institute, New York, NY
BACKGROUND: The relationship of muscle deoxygenation to maximum workload at peak exercise using near-infrared spectroscopy (NIRS) can provide insight into clinical populations with known exercise intolerance, but there are few studies available. PURPOSE: To characterize the relationship between change in muscle deoxygenation (deoxygenated hemoglobin; ΔHHb) and maximal workload achieved at peak exercise (MW). METHODS: 15 males and 3 females (mean+SD: 27.28±13.60 years [age]) underwent a cardiopulmonary exercise test (CPET) on a recumbent cycle ergometer. Measurements at peak exercise included ΔHHb of the left vastus lateralis using NIRS, MW (Watts), and oxygen uptake (VO2peak). We regressed ΔHHb on MW at peak exercise as the primary predictor with VO2peak as a covariate. We used a second order polynomial regression model to test for both linear and quadratic relationships. RESULTS: Participant characteristics (mean+SD) were as follows: ΔHHb =12.67+7.30 μmol, MW = 241.22+61.82 W, and VO2peak = 40.71+9.29 mL/kg/min. A polynomial model including ΔHHb, MW and VO2peak best characterized the relationship (F= 3.654, p= 0.05) where there appears to be an inflection point in the ΔHHb-MW relationship (see Figure 1). Each 30 W increase in workload was associated with 0.74 increase in ΔHHb up to 241 W, after which ΔHHb decreased curvilinearly (-0.172) with each further increase in 30 W. CONCLUSION: ΔHHb increases with incremental workload but appears to attenuate and slightly decrease at greater MW. It is possible that other factors may influence this relationship. Understanding how muscle deoxygenation, MW, and VO2peak are related at the time of peak exercise, or if other factors are contributing the differences in ΔHHb at higher workloads, may provide a foundation for uncovering the physiological mechanisms of local oxygen uptake in low and high exercise capacity individuals, and to assess exercise-limiting factors in clinical populations.
Supported by NIH Grant K01HD084690-01A1.
Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY
1- Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY
2- Department of Exercise Physiology, Shahid Beheshti University, Tehran, Iran
In the present coronavirus disease (COVID-19) pandemic, millions of people world-wide are being restricted to little social activity and stay-at-home orders. This means that the level of daily physical activity will be reduced considerably and very quickly compared to habitual life. Physical inactivity has been classified as a public health problem. (Physical Activity Guidelines for Americans, 2018) The excess fat with muscle loss along with the age-related decline of physical and functional capacity has been associated with increased risk of disability, morbidity and development of several chronic diseases (Global Recommendation on Physical Activity for Health, 2010). For these reasons, it’s important to describe the patterns and pervasiveness of sedentary behavior in Covid-19 survivors during the hospitalization and period following hospitalization, as well as determine whether these patterns are linked to musculoskeletal strength. Currently, no studies have examined the amount of time Covid-19 survivors engage in sedentary behaviors after hospitalization, a critical time period when lifestyle interventions ideally begin. Therefore, the purpose of this study is to investigate the relationship between prolonged physical inactivity, knee and ankle muscle strength, and body composition in Covid-19 survivors.