Change in energy expenditure and physical activity in response to aerobic and resistance exercise programs

Methods to Assess Energy Expenditure of Resistance Exercise: A Systematic Scoping Review

BACKGROUND

Nutrition guidance for athletes must consider a range of variables to effectively support individuals in meeting energy and nutrient needs. Resistance exercise is a widely adopted training method in athlete preparation and rehabilitation and therefore is one such variable that will influence nutrition guidance. Given its prominence, the capacity to meaningfully quantify resistance exercise energy expenditure will assist practitioners and researchers in providing nutrition guidance. However, the significant contribution of anaerobic metabolism makes quantifying energy expenditure of resistance exercise challenging.

OBJECTIVE

The aim of this scoping review was to investigate the methods used to assess resistance exercise energy expenditure.

METHODS

A literature search of Medline, SPORTDiscus, CINAHL and Web of Science identified studies that included an assessment of resistance exercise energy expenditure. Quality appraisal of included studies was performed using the Rosendal Scale.

RESULTS

A total of 19,867 studies were identified, with 166 included after screening. Methods to assess energy expenditure included indirect calorimetry (n = 136), blood lactate analysis (n = 25), wearable monitors (n = 31) and metabolic equivalents (n = 4). Post-exercise energy expenditure was measured in 76 studies. The reported energy expenditure values varied widely between studies.

CONCLUSIONS

Indirect calorimetry is widely used to estimate energy expenditure. However, given its limitations in quantifying glycolytic contribution, indirect calorimetry during and immediately following exercise combined with measures of blood lactate are likely required to better quantify total energy expenditure. Due to the cumbersome equipment and technical expertise required, though, along with the physical restrictions the equipment places on participants performing particular resistance exercises, indirect calorimetry is likely impractical for use outside of the laboratory setting, where metabolic equivalents may be a more appropriate method.

Comparative Analysis of Physical Activity, Performance-Related Health, and Academic Achievements in 11-to-13-Year-Old Schoolchildren in Qatar

Age-related differences in physical activity (PA), maturity status (PHV), physical performance (PP), and academic achievement (AA) among schoolchildren in Qatar were examined. Sixty-nine students from a school in Doha were categorized into three equal (n = 23) groups: 11-year-old students (U11; male: n = 14), 12-year-old students (U12: male: n = 7), and 13-year-old students (U13: male: n = 11). The testing process comprised a medicine ball throw, Stork balance test, hand grip strength test, the T-half test (PP), GPA in Arabic, mathematics, science (AA), International Physical Activity Questionnaire Short Form (PA), and Moore's equations (PHV). Relevant age-related differences (p < 0.001) were identified in mathematics, science, the T-half test, maturity, and arm span. Notably, differences between adjacent age groups were evident between U11 and U12, concerning arm span, maturity, mathematics, and science, and between U12 and U13 (the T-half test, mathematics, science). Concerning AP, the performance maxima were calculated for U12 (mathematics, science) and U11 (Arabic). Regarding PP, performance maxima were only observed for U13. Except for the moderate level, the highest levels of PA were detected in U13. Maturity status and anthropometric parameters did not differ significantly between age groups. However, AA demonstrated the most notable age-related differences. Specifically, mathematics showed substantial differences between adjacent age groups.

Differences in Physical Activity, Sedentary Behavior, Health-Related Physical Performance Indices and Academic Achievement: A Comparative Study of Normal-Weight and Obese Children in Qatar

Background: The relationship between physical activity (PA), health-related physical performance (PP), and academic achievement (AA) plays an important role in childhood. This study examined the differences in PA, sedentary behavior, health-related PP, maturity status, and AA between normal-weight and obese school children in Qatar. Methods: Eighty schoolchildren were recruited (age: 12.1 ± 0.6 years). Based on age-specific BMI percentiles, the children were classified as normal weight (n = 40) or obese (n = 40). Moore's equations were used to estimate their maturity status (PHV). The measurements encompassed anthropometric data as well as PP tests (medicine ball throw, postural stability, handgrip strength). AA was assessed by reviewing school records for grade point average in Mathematics, Science, and Arabic courses. The total amount of time spent participating in PA each week was calculated using the International Physical Activity Questionnaire Short Form. Results: Handgrip strength was the only parameter that showed a relevant group difference (p < 0.001, ηp2 = 0.15; normal weight: 19.7 ± 3.46 N; obese: 21.7 ± 2.80 N). We found only one moderate correlation between PHV and handgrip strength (r = 0.59). Conclusions: The findings suggest that obesity status alone might not serve as a sufficient predictor of AA in school or PA levels.

Compensatory mechanisms from different exercise intensities in type 2 diabetes: a secondary analysis of a 1-year randomized controlled trial

AIMS

This investigation aimed to determine the effect of different intensities of training on non-exercise physical activity (NEPA) and estimated thermogenesis (NEAT) from a 1-year exercise randomized controlled trial (RCT) in individuals with type 2 diabetes mellitus (T2DM) on non-training days. Additionally, changes in NEPA and estimated NEAT in those who failed (low-responders) or succeeded (high-responders) in attaining exercise-derived clinically meaningful reductions in body weight (BW) and fat mass (FM) (i.e., 6% for FM and 3% for BW) was assessed.

METHODS

Individuals with T2DM (n = 80) were enrolled in a RCT with three groups: resistance training combined with moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) and a control group. Of the 80 participants, 56 (completed data) were considered for this secondary analysis. NEPA and estimated NEAT were obtained by accelerometry and body composition through dual-energy X-ray absorptiometry.

RESULTS

After adjustments, no time*group interactions were found for estimated NEAT in the MICT (β = - 5.33, p = 0.366) and HIIT (β = - 5.70, p = 0.283), as well as for NEPA in the MICT (β = - 452.83, p = 0.833) and HIIT (β = - 2770.76, p = 0.201), when compared to controls. No compensatory changes in NEPA and estimated NEAT were observed when considering both low-responders and high-responders to FM and BW when compared to controls.

CONCLUSIONS

Both MICT and HIIT did not result in any compensatory changes in estimated NEAT and NEPA with the intervention on non-training days. Moreover, no changes in estimated NEAT and NEPA were found when categorizing our participants as low-responders and high-responders to FM and BW when compared to controls. Trial registration clinicaltrials.gov ID. NCT03144505.

The Effects of an Acute Bout of Aerobic or Resistance Exercise on Nonexercise Physical Activity

Introduction/Purpose

A reduction in nonexercise physical activity (NEPA) after exercise may reduce the effectiveness of exercise interventions on weight loss in adults with overweight or obesity. Aerobic exercise (AEx) and resistance exercise (REx) may have different effects on NEPA. The purpose of this secondary analysis was to examine the effect of a single bout of AEx or REx on NEPA and sedentary behavior in inactive adults with overweight or obesity.

Methods

Adults with overweight or obesity (n = 24; 50% male; age, 34.5 ± 1.5 yr; body mass index, 28.5 ± 0.9 kg·m-2) not meeting current physical activity guidelines completed a single 45-min bout of AEx, REx, or a sedentary control on different days in random order. After each condition, participants' NEPA was recorded for 84 h by accelerometer. Time spent sedentary and in light, moderate, and vigorous physical activity; steps; metabolic equivalent of task (MET)-hours; and sit-to-stand transitions were calculated using activity count data.

Results

No differences were observed in the percent of waking time spent sedentary and in light, moderate, and vigorous activity between conditions (P > 0.05). No differences were observed in steps, MET-hours, or sit-to-stand transitions between conditions (P > 0.05). NEPA responses were variable among individuals, with approximately half of participants reducing and half increasing NEPA over the 84 h after each exercise condition.

Conclusion

NEPA was not reduced after an acute bout of AEx or REx in a sample of inactive adults with overweight or obesity.

The Difference in the Prevalence of Metabolic Syndrome According to Meeting Guidelines for Aerobic Physical Activity and Muscle-Strengthening Exercise: A Cross-Sectional Study Performed Using the Korea National Health and Nutrition Examination Survey, 2014-2019

Physical activity and muscle strengthening are essential for preventing and managing metabolic syndrome. This study was conducted to investigate the relationship between the prevalence of metabolic syndrome and meeting the guidelines for aerobic physical activity (APA), muscle strengthening exercise (MSE), and combined exercise. We used data from 22,467 Koreans aged 40 years or older, who participated in in the Korea National Health and Nutrition Examination Survey (KNHANES) 2014-2019. We used the Global Physical Activity Questionnaire (GPAQ) to measure physical activity and surveyed frequency of MSE through a questionnaire. Metabolic syndrome was defined according to the American heart association and the National Heart, Lung, and Blood Institute. Compared with none exercise group, odds ratios of APA, MSE, and combined exercise group (CEG) on metabolic syndrome prevalence were 0.85 (95% confidence interval (CI), 0.74-0.98), 0.81 (95% CI, 0.67-0.99), and 0.65 (95% CI, 0.54-0.78) among men, respectively. Among women, ORs of APA, MSE, and CEG were 0.83 (95% CI, 0.73-0.93), 0.73 (95% CI, 0.58-0.91), and 0.74 (95% CI, 0.58-0.93), respectively. This study showed that meeting guidelines for APA and MSE was associated with lower prevalence of metabolic syndrome. Furthermore, subjects who met both APA and MSE had the lowest metabolic syndrome prevalence.

Compensatory effects of different exercise durations on non-exercise physical activity, appetite, and energy intake in normal weight and overweight adults

Objectives: To examine compensatory changes of different exercise durations on non-exercise physical activity (NEPA), appetite, and energy intake (EI) in normal and overweight adults, and to determine if different body mass index of individuals interact with these compensatory effects.

Methods: Ten normal weight adults (nine females and one male; age: 24.0 ± 0.4 years; BMI: 20.7 ± 0.5 kg/m²) and ten overweight adults (six females and four males; age: 24.5 ± 0.9 years; BMI: 25.9 ± 0.4 kg/m²) participated in this study. The participants completed two exercise trials: short-duration continuous training (SDCT) and long-duration continuous training (LDCT), i.e., a 40 min short-duration and an 80 min long-duration continuous training in a randomized order. Total physical activity and NEPA were monitored using an accelerometer for seven consecutive days, which involved a two-day baseline observation period (C-pre-Ex), three-day exercise intervention period (Ex), and two-day follow-up period (C-post-Ex). Blood samples were collected for appetite-related hormone analysis. Appetite score was assessed using the visual analogue scale. Energy intake was evaluated by weighing the food and recording diaries.

Results: The NEPA evaluation showed that it was higher for SDCT than for LDCT in the C-post-Ex period (F (1, 19) = 8.508, p = 0.009) in the total sample. Moreover, results also indicated that NEPA was lower for LDCT (F (2, 18) = 6.316, p = 0.020) and higher for SDCT (F (2, 18) = 3.889, p = 0.026) in the C-post-Ex period than in the C-pre-Ex and Ex periods in overweight group. Acyl-ghrelin revealed a main effect of time in the total sample and in normal weight and overweight groups; it was lower in the C-post-Ex period than in the C-pre-Ex and Ex periods (all p < 0.05). Total EI analysis revealed no significant changes in either the total sample or in the normal weight and overweight groups.

Conclusion: These findings demonstrate that short duration exercise led to a compensatory increment in NEPA, whereas long duration exercise induced a compensatory decrease in NEPA. Moreover, there was a higher and delayed compensatory response in overweight adults than in normal weight adults. Nevertheless, energy intake was not changed across time, regardless of exercise duration.

Mechanical and Structural Remodeling of Cardiac Muscle after Aerobic and Resistance Exercise Training in Rats

INTRODUCTION

Aerobic and resistance exercise training results in distinct structural changes of the heart. The mechanics of how cardiac cells adapt to resistance training and the benefits to cells when combining aerobic and resistance exercise remains largely unknown. The purpose of this study was to compare mechanical adaptations of skinned cardiac fiber bundles after chronic resistance, aerobic and combined exercise training in rats. We hypothesized that differences in mechanical function on the fiber bundle level coincide with differences previously reported in the structure of the heart.

METHOD

Twelve-week-old rats were assigned to (i) an aerobic running group (n = 6), (ii) a ladder climbing resistance group (n = 6), (iii) a combination group subjected to aerobic and resistance training (n = 6), or (iv) a sedentary (control) group (n = 5). Echocardiography was used to measure cardiac structural remodeling. Skinned cardiac fiber bundles were used to determine active and passive force properties, maximal shortening velocity, and calcium sensitivity.

RESULTS

Aerobically trained animals had 43%-49% greater ventricular volume and myocardial thickness, and a 4%-17% greater shortening velocity and calcium sensitivity compared with control group rats. Resistance-trained rats had 37%-71% thicker ventricular walls, a 56% greater isometric force production, a 9% greater shortening velocity, and a 4% greater calcium sensitivity compared with control group rats. The combination exercise-trained rats had 25%-43% greater ventricular volume and myocardial wall thickness, a 55% greater active force production, a 7% greater shortening velocity, and a 60% greater cross-bridge cooperativity compared with control group rats.

CONCLUSIONS

The heart adapts differently to each exercise modality, and a combination of aerobic and resistance training may have the greatest benefit for cardiac health and performance.

Morning fatigue and structured exercise interact to affect non-exercise physical activity of fit and healthy older adults

Background

Exercise training is crucial for maintaining physical and mental health in aging populations. However, as people participate in structured exercise training, they tend to behaviorally compensate by decreasing their non-exercise physical activity, thus potentially blunting the benefits of the training program. Furthermore, physical activity of older adults is substantially influenced by physical feelings such as fatigue. Nevertheless, how older people react to day-to-day fluctuations of fatigue and whether fatigue plays a role in non-exercise physical activity compensation is not known. Thus, the purpose of this study was twofold: (1) To explore whether the volume and intensity of habitual physical activity in older adults were affected by morning fatigue. (2) To investigate the effect of attending power and resistance exercise sessions on the levels of non-exercise physical activity later that day and the following day.

Methods

Twenty-eight older adults wore an accelerometer during a 4-week low-volume, low-intensity resistance and power training program with three exercise sessions per week and for 3 weeks preceding and 1 week following the program. During the same period, the participants were prompted every morning, using text messages, to rate their momentary fatigue on a scale from 0 to 10.

Results

Greater morning fatigue was associated with lower volume (p = 0.002) and intensity (p = 0.017) of daily physical activity. Specifically, one point greater on the fatigue scale was associated with 3.2 min (SE 1.0) less moderate-to-vigorous physical activity. Furthermore, attending an exercise session was associated with less moderate-to-vigorous physical activity later that day by 3.7 min (SE 1.9, p = 0.049) compared to days without an exercise session. During the next day, the volume of physical activity was greater, but only in participants with a body mass index up to 23 (p = 0.008).

Conclusions

Following low-volume exercise sessions, fit and healthy older adults decreased their non-exercise physical activity later that day, but this compensation did not carry over into the next day. As momentary morning fatigue negatively affects daily physical activity, we suggest that the state level of fatigue should be monitored during intensive exercise programs, especially in less fit older adults with increased fatigability.

Feasibility, Usability, and Enjoyment of a Home-Based Exercise Program Delivered via an Exercise App for Musculoskeletal Health in Community-Dwelling Older Adults: Short-term Prospective Pilot Study

Background

Many older adults choose and prefer to exercise at home, but to attain the greatest benefits, the correct type and dose of exercise should be prescribed and adherence maintained. Advances in digital health technologies now provide the opportunity for exercise professionals to deliver and monitor personalized, evidence-based exercise programs to anyone at any time.

Objective

The aim of this study was to evaluate the feasibility, usability, and enjoyment of a web-based exercise prescription app as a platform for exercise professionals to remotely deliver and monitor an individually tailored, home-based multicomponent exercise program (delivered through tablet computers) to older adults living independently in the community.

Methods

This was an 8-week, prospective single-arm pilot study in 20 adults aged ≥65 years living independently in the community: 10 owned a tablet computer (tablet owners) and 10 did not own tablets (tablet nonowners). All participants were prescribed a home-based, muscle strengthening, weight-bearing impact and challenging balance/mobility program (3 days/week) using a commercial exercise prescription app on a tablet computer. Study endpoints were feasibility (retention, adherence, adverse events), usability (System Usability Scale), physical activity enjoyment (Physical Activity Enjoyment Scale), changes in lower extremity function (Short Physical Performance Battery [SPPB]), and level of physical activity (questionnaire). Process measures related to the participants' experiences and perceptions of the exercise program and web-based app were also included.

Results

A total of 19 participants (mean age, 70 years) completed the study (19/20, 95%), and mean adherence to the exercise program was 84% (95% CI 70%-97%). There were 2 minor adverse events in 2 participants from 401 completed sessions. Mean weekly walking time increased by 78 minutes (95% CI 0-156, P=.049) and moderate-to-vigorous physical activity time by 41 minutes (95% CI –8 to 90, P=.09). For SPPB scores, there was a 0.3 point (95% CI –0.1 to 0.7, P=.17) modest sized (effect size, d=0.42) improvement after 8 weeks. Mean (SD) system usability was high (86 [10] with 100 best imaginable). There was no change in the overall physical activity enjoyment scores after 8 weeks, but participants reported that they enjoyed using the web-based exercise app and the exercise program (median score 4 on a 5-point Likert scale). For all measures, there were no differences between previous tablet owners and nonowners.

Conclusions

This pilot feasibility study indicates that it is safe and feasible for community-dwelling older adults to participate in a home-based, multicomponent exercise program targeting musculoskeletal health and function that was delivered and monitored remotely by exercise professionals using a tablet-based exercise prescription app.

Training-induced changes in daily energy expenditure: Methodological evaluation using wrist-worn accelerometer, heart rate monitor, and doubly labeled water technique

INTRODUCTION

Wrist-mounted motion sensors can quantify the volume and intensity of physical activities, but little is known about their long-term validity. Our aim was to validate a wrist motion sensor in estimating daily energy expenditure, including any change induced by long-term participation in endurance and strength training. Supplemental heart rate monitoring during weekly exercise was also investigated.

METHODS

A 13-day doubly labeled water (DLW) measurement of total energy expenditure (TEE) was performed twice in healthy male subjects: during two last weeks of a 12-week Control period (n = 15) and during two last weeks of a 12-week combined strength and aerobic Training period (n = 13). Resting energy expenditure was estimated using two equations: one with body weight and age, and another one with fat-free mass. TEE and activity induced energy expenditure (AEE) were determined from motion sensor alone, and from motions sensor combined with heart rate monitor, the latter being worn during exercise only.

RESULTS

When body weight and age were used in the calculation of resting energy expenditure, the motion sensor data alone explained 78% and 62% of the variation in TEE assessed by DLW at the end of Control and Training periods, respectively, with a bias of +1.75 (p <.001) and +1.19 MJ/day (p = .002). When exercise heart rate data was added to the model, the combined wearable device approach explained 85% and 70% of the variation in TEE assessed by DLW with a bias of +1.89 and +1.75 MJ/day (p <.001 for both). While significant increases in TEE and AEE were detected by all methods as a result of participation in regular training, motion sensor approach underestimated the change measured by DLW: +1.13±0.66 by DLW, +0.59±0.69 (p = .004) by motion sensor, and +0.98±0.70 MJ/day by combination of motion sensor and heart rate. Use of fat-free mass in the estimation of resting energy expenditure removed the biases between the wearable device estimations and the golden standard reference method of TEE and demonstrated a training-induced increase in resting energy expenditure by +0.18±0.13 MJ/day (p <.001).

CONCLUSIONS

Wrist motion sensor combined with a heart rate monitor during exercise sessions, showed high agreement with the golden standard measurement of daily TEE and its change induced by participation in a long-term training protocol. The positive findings concerning the validity, especially the ability to follow-up the change associated with a lifestyle modification, can be considered significant because they partially determine the feasibility of wearable devices as quantifiers of health-related behavior.

Taurine supplementation increases irisin levels after high intensity physical training in obese women

BACKGROUND

Irisin is a myokine/adipokine that under stimulus of physical exercise is able to improve thermogenic capacity in adipose tissue. Likewise, taurine supplementation has demonstrated similar effects on energy metabolism. Therefore, we hypothesized that taurine supplementation combined with physical training may induce an increase in irisin concentrations, optimizing energy metabolism in obese individuals.

OBJECTIVE

To evaluate if taurine supplementation associated with a high intensity physical training program increases irisin levels in obese women.

METHODS

double-blind study with 22 obese women (BMI 32.4 ± 2.0 kg/m², 36.6 ± 6.4 years and sedentary) who were randomly divided into two groups, control group (GC, n = 14), exercised and supplemented with placebo (3 g of starch), and taurine group (GTAU, n = 8), exercised and supplemented with taurine (3 g). The subjects performed high intensity physical training, Deep Water Running (DWR), for 8 weeks, 3 times/week, for 50 min per training session, at 70-85% maximum heart rate. Resting metabolic rate (RMR) was evaluated by indirect calorimetry, body composition by deuterium oxide, plasma taurine by HPLC, plasma irisin by Multiplex Kit, and food consumption by food records. The results were analyzed by an ANOVA two way repeated measures mixed model, with the Sidak post hoc (p < 0.05).

RESULTS

No changes were observed in body composition. DWR increased RMR independent of supplementation (p < 0.001) and irisin levels (pg/mL) showed a significant difference only in the GTAU in 1 h after exercise (p < 0.001).

CONCLUSION

DWR associated with taurine supplementation resulted in increased plasma irisin concentrations after physical training in obese adult women.

The Metabolomic Signatures of Weight Change

Obesity represents a major health concern, not just in the West but increasingly in low and middle income countries. In order to develop successful strategies for losing weight, it is essential to understand the molecular pathogenesis of weight change. A number of pathways, implicating oxidative stress but also the fundamental regulatory of insulin, have been implicated in weight gain and in the regulation of energy expenditure. In addition, a considerable body of work has highlighted the role of metabolites generated by the gut microbiome, in particular short chain fatty acids, in both processes. The current review provides a brief understanding of the mechanisms underlying the associations of weight change with changes in lipid and amino acid metabolism, energy metabolism, dietary composition and insulin dynamics, as well as the influence of the gut microbiome. The changes in metabolomic profiles and the models outlined can be used as an accurate predictor for obesity and obesity related disorders.

Resistance Training Reduces Skeletal Muscle Work Efficiency in Weight-Reduced and Non-Weight-Reduced Subjects

OBJECTIVE

The objective of this study is to determine whether resistance training is similarly effective in reducing skeletal muscle efficiency and increasing strength in weight-reduced and maximal weight subjects.

METHODS

This study examined the effects of supervised resistance exercise on skeletal muscle in 14 individuals with overweight and obesity sustaining a 10% or greater weight loss for over 6 months and a phenotypically similar group of 15 subjects who had not reduced weight and were weight stable at their maximal lifetime body weight. We assessed skeletal muscle work efficiency and fuel utilization (bicycle ergometry), strength (dynamometry), body composition (dual energy x-ray absorptiometry), and resting energy expenditure (indirect calorimetry) before and after 12 weeks of thrice-weekly resistance training.

RESULTS

Non-weight-reduced subjects were significantly (10%-20%) stronger before and after the intervention than reduced-weight subjects and gained significantly more fat-free mass with a greater decline in percentage of body fat than weight-reduced subjects. Resistance training resulted in similar significant decreases (~10%) in skeletal muscle work efficiency at low-level exercise and ~10% to 20% increases in leg strength in both weight-reduced and non-weight-reduced subjects.

CONCLUSIONS

Resistance training similarly increases muscle strength and decreases efficiency regardless of weight loss history. Increased resistance training could be an effective adjunct to reduced-weight maintenance therapy.

Exercise, energy balance and body composition

Activity-induced energy expenditure, as determined by the activity pattern including exercise, is the most variable component of daily energy expenditure. Here, the focus is on effects of exercise training on energy balance and body composition in subjects with a sedentary or light-active lifestyle. Then, exercise training induces an energy imbalance consistently lower than prescribed energy expenditure from exercise. Additionally, individual responses are highly variable and decrease in time. Combining the results from 23 exercise training studies in normal-weight, overweight, and obese subjects, varying in duration from 2 to 64 weeks, showed an average initial energy imbalance of about 2 MJ/day with an exponential decline to nearly zero after about 1 year. A compensatory increase in energy intake is the most likely explanation for the lower than expected effect of exercise on energy balance. Overall, exercise training results in a healthier body composition as reflected by a reduction of body fat, especially in overweight and obese subjects, with little or no long-term effect on body weight.

Increases in Physical Activity Result in Diminishing Increments in Daily Energy Expenditure in Mice

Exercise is a common component of weight loss strategies, yet exercise programs are associated with surprisingly small changes in body weight [1-4]. This may be due in part to compensatory adaptations, in which calories expended during exercise are counteracted by decreases in other aspects of energy expenditure [1, 5-10]. Here we examined the relationship between a rodent model of voluntary exercise- wheel running- and total daily energy expenditure. Use of a running wheel for 3 to 7 days increased daily energy expenditure, resulting in a caloric deficit of ∼1 kcal/day; however, total daily energy expenditure remained stable after the first week of wheel access, despite further increases in wheel use. We hypothesized that compensatory mechanisms accounted for the lack of increase in daily energy expenditure after the first week. Supporting this idea, we observed a decrease in off-wheel ambulation when mice were using the wheels, indicating behavioral compensation. Finally, we asked whether individual variation in wheel use within a group of mice would be associated with different levels of daily energy expenditure. Despite a large variation in wheel running, we did not observe a significant relationship between the amount of daily wheel running and total daily energy expenditure or energy intake across mice. Together, our experiments support a model in which the transition from sedentary to light activity is associated with an increase in daily energy expenditure, but further increases in physical activity produce diminishingly small increments in daily energy expenditure.

Do Running and Strength Exercises Reduce Daily Muscle Inactivity Time?

Understanding how a specific exercise changes daily activity patterns is important when designing physical activity interventions. We examined the effects of strength and interval running exercise sessions on daily activity patterns using recordings of quadriceps and hamstring muscle electromyographic (EMG) activity and inactivity. Five male and five female subjects taking part in a 10-week training programme containing both strength and interval running training sessions were measured for daily muscle EMG activities during three days: on a strength day, an interval running day, and a day without exercise. EMG was measured using textile electrodes embedded into sport shorts that were worn 9.1 ± 1.4 hours/day and results are given as % of recording time. During the total measurement time the muscles were inactive 55 ± 26%, 53 ± 30% and 71 ± 12% during strength training day, interval running day, and day without exercise (n.s.). When compared to the day without exercise, the change in muscle inactivity correlated negatively with change in light muscle activity in strength (r = -0.971, p < 0.001) and interval running days (r = -0.965, p < 0.001). While interval running exercise bout induced a more systematic decrease in muscle inactivity time (from 62 ± 15% to 6 ± 6%, p < 0.001), reductions in muscle inactivity in response to strength exercise were highly individual (range 5–70 pp) despite the same training programme. Strength, but not running exercise bout, increased muscle activity levels occurring above 50% MVC (p < 0.05) when compared to a similar period without exercise. The effect of strength exercise bout on total daily recording time increased the EMG amplitudes across the entire intensity spectrum. While strength and interval running exercise are effective in increasing muscle moderate-to-vigorous activity when compared to a similar period without exercise, it comprises only a small part of the day and does not seem to have a systematic effect neither to reduce nor induce compensatory increase in the daily muscle inactivity that is highly heterogeneous between individuals.

Aerobic Exercises for Cognition Rehabilitation following Stroke: A Systematic Review

BACKGROUND

Cognitive impairments are highly prevalent in stroke survivors and can substantially affect their physical rehabilitation and quality of life. The management of these impairments currently remains limited, but increasing studies reported the effect of aerobic exercise on cognitive performance in patients suffering from stroke. The purpose of this review was to assess the effects of aerobic exercise on cognitive function following stroke.

METHODS

Seven electronic databases (China National Knowledge Infrastructure [CNKI], Chinese Science and Technology Periodical Database [VIP], Wanfang, China Biology Medicine disc [CBM], Science Citation Index [SCI], EMBASE, and PubMed) were searched from their inception to May 31, 2015, for the effects of aerobic exercise on cognitive ability compared to usual physical activity in stroke survivors. RevMan V5.3 (The Nordic Cochrane Centre) was used to analyze the data and to evaluate the methodological quality of the included studies.

RESULTS

Ten eligible studies including 394 participants were identified. Six studies showed that aerobic exercise significantly improved global cognitive ability in stroke survivors. Four studies reported aerobic exercise to be beneficial in improving memory, but only one showed statistical significance. Two studies investigated the effects of aerobic exercise on attention, and one showed a significant improvement. One study reported a significant benefit of aerobic exercise on visuospatial ability in stroke survivors. No adverse events were reported in the included studies.

CONCLUSIONS

Aerobic exercise may have a positive effect on improving global cognitive ability and a potential benefit on memory, attention, and the visuospatial domain of cognition in stroke survivors. However, further large, rigorously designed trials are needed to confirm these findings.

The effects of aerobic exercise on the structure and function of DMN-related brain regions: a systematic review

Physical activity may play a role in both the prevention and slowing of brain volume loss and may be beneficial in terms of improving the functional connectivity of brain regions. But much less is known about the potential benefit of aerobic exercise for the structure and function of the default mode network (DMN) brain regions. This systematic review examines the effects of aerobic exercise on the structure and function of DMN brain regions in human adulthood. Seven electronic databases were searched for prospective controlled studies published up to April 2015. The quality of the selected studies was evaluated with the Cochrane Collaboration's tool for assessing the risk of bias. RevMan 5.3 software was applied for data analysis. Finally, 14 studies with 631 participants were identified. Meta-analysis revealed that aerobic exercise could significantly increase right hippocampal volume (SMD = 0.26, 95% CI 0.01-0.51, p = 0.04, I² = 7%, 4 studies), and trends of similar effects were observed in the total (SMD = 0.12, 95% CI -0.17 to 0.41, p = 0.43, I² = 0%, 5 studies), left (SMD = 0.12, 95% CI -0.13 to 0.37, p = 0.33, I² = 14%, 4 studies), left anterior (SMD = 0.12, 95% CI -0.16 to 0.40, p = 0.41, I² = 74%, 2 studies) and right anterior (SMD = 0.10, 95% CI -0.17 to 0.38, p = 0.46, I² = 76%, 4 studies) hippocampal volumes compared to the no-exercise interventions. A few studies reported that relative to no-exercise interventions, aerobic exercise could significantly decrease the atrophy of the medial temporal lobe, slow the anterior cingulate cortex (ACC) volume loss, increase functional connectivity within the hippocampus and improve signal activation in the cingulate gyrus and ACC. The current review suggests that aerobic exercise may have positive effects on the right hippocampus and potentially beneficial effects on the overall and other parts of the hippocampus, the cingulate cortex and the medial temporal areas of the DMN. Moreover, aerobic exercise may increase functional connectivity or activation in the hippocampus, cingulate cortex and parahippocampal gyrus regions of the DMN. However, considering the quantity and limitations of the included studies, the conclusion could not be drawn so far. Additional randomized controlled trials (RCTs) with rigorous designs and longer intervention periods are needed in the future.