Metabolic flexibility in response to resistance training plus photobiomodulation therapy in sedentary elderly women: a pilot study

Abstract

The study aimed to evaluate the metabolic flexibility of sedentary elderly women in response to resistance training (RT) plus photobiomodulation therapy (PBMT) or RT alone, after two months of intervention. Nineteen elderly women were allocated into two groups, RT (n = 9, 68.44 {+/-} 5.27 years old) and RT plus PBMT (RTPT) (n = 10, 69.40 {+/-} 5.21 years old). The RTPT group received the PBMT, while for the RT group, the equipment was turned off. An incremental treadmill test together with a gas analyzer was performed to record variables such as heart rate (HR), oxygen consumption (VO2), carbon dioxide production (VCO2) and power output (PO) at the anaerobic threshold (AT), respiratory compensation point (RCP) and maximal oxygen consumption (VO2max), and thus indirectly verify metabolic flexibility. In comparison with baseline RTPT displayed significant differences in VO2max (pre: 18.32 {+/-} 3.01; post: 21.89 {+/-} 2.35), carbohydrate oxidation (CHox) (pre: 1.54 {+/-} 0.61; post: 2.45 {+/-} 0.91), CHox/FFM (fat-free mass) (pre: 36.12 {+/-} 12.28; post: 55.92 {+/-} 16.74) and energy expenditure normalized to FFM, EE/FFM (pre: 147.00 {+/-} 49.95; post: 227.56 {+/-} 68.08) during maximum effort incremental testing, while the RT group did not demonstrate a significant difference in these variables.The intervention with RT plus PBMT seems to result in a positive impact on metabolic variables in sedentary elderly women when compared with RT alone, making this approach a viable alternative to improve VO2max, CHox, CHox/FFM and EE/FFM during maximal effort testing. Author summaryAn aging-related decline in metabolic flexibility may reduce the ability to efficiently use energy during exercise, contributing to lower physical capacity and increased health risks in older adults. Resistance training is widely recommended for elderly populations, but additional strategies may further improve metabolic and physiological adaptations. This study investigated whether combining resistance training with photobiomodulation therapy could improve metabolic responses in sedentary elderly women more effectively than resistance training alone. Participants completed two months of supervised training, and metabolic responses were evaluated during an incremental exercise test. Women who received both resistance training and photobiomodulation therapy showed greater improvements in maximal oxygen consumption, carbohydrate oxidation, and energy expenditure during maximal exercise compared with those who performed resistance training alone. These findings suggest that photobiomodulation therapy may enhance the physiological adaptations associated with resistance training. The results indicate that combining resistance training with photobiomodulation therapy may represent a promising non-invasive strategy to improve exercise metabolism and functional capacity in sedentary elderly women. Further studies with larger samples are needed to confirm these findings and clarify the mechanisms involved.