Mechanical efficiency improvement in relation to metabolic changes in sedentary obese adults

Abstract

PurposeMechanical efficiency (ME) refers to the ability of an individual to transfer energy consumed by external work. This performance indicator is impaired by obesity and is associated with decreased high-intensity exercise performance. However, it is unclear if ME may be improved in response to high intensity training (HIT). This study aimed to determine if ME increases in response to HIT in obese adults and to identify the factors associated with these changes.Methods24 obese adults (body mass index=∼33 kg/m2) were randomised into control (n=12) and trained (n=12) groups. Following baseline metabolic, anthropometric, fitness and ME measurements, the participants completed a 6-week exercise intervention that included 18 sessions of six repeats of 6 s supramaximal sprints on an electromagnetically braked cycle ergometer. The metabolic, anthropometric and fitness assessments were repeated postintervention. ME (expressed as a %) was calculated during an incremental maximal cycling test at stages of 25, 50, 75, 100 and 125 W.ResultsME did not differ across the groups at 25 and 50 W. Following HIT, ME increased significantly at 75, 100 and 125 W (p<0.01, respectively) compared with the control group (p<0.01, respectively). Although no changes in fat-free mass were observed following HIT, the increases in ME at 75, 100 and 125 W correlated positively with both homeostasis model assessment-estimated insulin resistance index decreases (r=0.9; r=0.89 and r=0.88, p<0.01, respectively) and peak power increases (r=0.87, r=0.88 and r=0.9, p<0.01, respectively).ConclusionsAlthough there were no changes in the participants’ anthropometric variables, HIT improved ME in obese adults, an enhancement that appears to be related to increases in muscle strength and metabolic adaptations.

High-intensity interval training improves performance in young and older individuals by increasing mechanical efficiency

“…To the best of our knowledge, no data has been reported regarding ME values in response to interventions in older populations. According to our previous data, improvements in ME observed in response to HIIT could be attributed to improvements in the metabolic milieu (HOMA‐IR), without excluding increases in muscle performance (Jabbour and Iancu ). In fact, alterations in metabolic milieu may impair substrate use (e.g., carbohydrate) and muscle performance; therefore, HIIT may improve these parameters (Jensen et al.…”

“…The laboratory temperatures were kept stable (20 ± 2°C). The same training protocol has been previously developed and tested by our laboratory (Jabbour and Iancu ; Jabbour et al. ).…”

Eco-Friendly Power Generator Cum Fitness Analyzer

“…Overweight and obesity are often associated with low levels of physical activity [5]. Obesity decreases mechanical efficiency refers to the ability of an individual to transfer energy consumed by external work and high intensity exercise performance [6]. Obesity is also associated with musculoskeletal structure changes, decreased mobility, modification of the gait pattern, and changes in energy expenditure for a given activity [5].…”

Mechanical efficiency of high versus moderate intensity aerobic exercise in coronary heart disease patients: A randomized clinical trial

“…A decreased ME, which indicates that more energy is consumed at a given work output, could represent an increased energy cost of breathing during exercise, an altered efficiency in ATP production (ATP produced per O 2 consumed), or a higher ATP cost of contraction (ATP consumed per work output) [1]. Therefore, individuals with lower ME values should be less efficient in respect to performance and may therefore be limited in terms of physical activity [2]. Consequently, the evaluating ME may be valuable for the detection of muscle dysfunction and the assessment of any subsequent adaptations in response to training [3].…”

“…These adaptations are likely the result of skeletal muscle adaptations related to metabolic improvement associated with strengthening of muscle. Given that metabolic environment and muscle function may condition muscle performance and muscle energy profile of an individual, it is possible that any improvement in these parameters may be predictive of a subsequent increase in ME [2]. Therefore, ME may also be an important predictor of efficacy and may provide relevant data regarding performance and energy use adaptations in response to training [2].…”