Arm and Intensity-Matched Leg Exercise Induce Similar Inflammatory Responses

Dissonance in views between healthcare professionals and adults with a spinal cord injury with their understanding and interpretation of exercise intensity for exercise prescription

Objectives

To evaluate the difference between healthcare professionals (HCPs) and adults with spinal cord injury (SCI) in Asia regarding knowledge and interpretation of 'exercise intensity' for aerobic exercise prescription.

Methods and study design

A survey was distributed to practising HCP and adults with SCI. It was completed in participants' local language on topics related to the importance of exercise frequency, intensity, time and type; methods for monitoring and terms related to exercise intensity prescription. χ² analysis was used to detect differences in HCP or those with SCI.

Results

121 HCP and 107 adults with an SCI ≥1 years (C1-L4) participated. Responses revealed 61% of all HCP ranked 'intensity' being most important whereas only 38% respondents from the SCI group ranked it as high importance (p=0.008). For those with SCI, 'frequency' was most important (61%) which was significantly higher than the 45% selected by HCPs (p=0.030). Of the 228 respondents on average only 34% believed that the terms, 'moderate' and 'vigorous' provided enough information for aerobic exercise intensity prescription. HCP most often used HR methods compared with the SCI group (90% vs 54%; p<0.01). Both groups frequently used the subjective measures of exercise intensity, for example, Ratings of Perceived Exertion (8%3 vs 76% for HCP and SCI), HCP also frequently used speed (81%) and SCI also frequently relied on 'the affect' or feelings while exercising (69%).

Conclusions

These differences must be considered when developing clinical-practice exercise guidelines and health referral educational pathways for adults with SCI in Asia.

F, Leicht CA. Serum and plasma brain-derived neurotrophic factor concentration are elevated by systemic but not local passive heating

Brain-derived neurotrophic factor (BDNF) plays a key role in neuronal adaptations. While previous studies suggest that whole-body heating can elevate circulating BDNF concentration, this is not known for local heating protocols. This study investigated the acute effects of whole-body versus local passive heating on serum and plasma BDNF concentration. Using a water-perfused suit, ten recreationally active males underwent three 90 min experimental protocols: heating of the legs with upper-body cooling (LBH), whole-body heating (WBH) and a control condition (CON). Blood samples were collected before, immediately after and 1 h post-heating for the determination of serum and plasma BDNF concentration, platelet count as well as the BDNF release per platelet. Rectal temperature, cardiac output and femoral artery shear rate were assessed at regular intervals. Serum and plasma BDNF concentration were elevated after WBH (serum: 19.1±5.0 to 25.9±11.3 ng/ml, plasma: 2.74±0.9 to 4.58±2.0; p<0.044), but not LBH (serum: 19.1±4.7 to 22.3±4.8 ng/ml, plasma: 3.25±1.13 to 3.39±0.90 ng/ml; p>0.126), when compared with CON (serum: 18.6±6.4 to 16.8±3.4 ng/ml, plasma: 2.49±0.69 to 2.82±0.89 ng/ml); accompanied by an increase in platelet count (p<0.001). However, there was no change in BDNF content per platelet after either condition (p = 0.392). All physiological measures were elevated to a larger extent after WBH compared with LBH (p<0.001), while shear rate and rectal temperature were higher during LBH than CON (p<0.038). In conclusion, WBH but not LBH acutely elevates circulating BDNF concentration. While these findings further support the use of passive heating to elevate BDNF concentration, a larger increase in shear rate, sympathetic activity and/or rectal temperature than found after LBH appears needed to induce an acute BDNF response by passive heating.

Effects of intensity-matched exercise at different intensities on inflammatory responses in able-bodied and spinal cord injured individuals

Objective: To compare the effects of intensity-matched acute exercise at different intensities on proinflammatory and anti-inflammatory cytokines between able-bodied (AB) and spinal cord injured (SCI) individuals.Design: Non-Randomized Controlled Trial.Setting: Community settings in São Paulo - Brazil.Participants: Eight AB and nine SCI paraplegic.Interventions: Participants underwent three exercise sessions at different relative intensities: at ventilatory threshold 1 intensity (VT1), 15% below VT1, and 15% above VT1. Similar energy expenditures were established from exercises with different intensities for each volunteer. The AB group was tested on a conventional treadmill, whereas the SCI group was tested on a treadmill adapted for wheelchair use. Blood samples were collected at baseline, immediately after, and 30 min after the exercise sessions.Outcome measures: Interleukin 1 receptor antagonist, interleukin 1 beta, interleukin 2, interleukin 4, interleukin 6, interleukin 10 and tumoral necrosis factor alpha were measured.Results: When groups were compared, interleukin - 2 was found higher, whereas interleukin - 4 and interleukin - 10 were found lower in the SCI group at all collection times in the three exercise intensities (all P < 0.05). Interleukin - 1 receptor antagonist was found higher immediately after exercise at VT1, 15% above VT1 and 30 min after 15% below VT1 in the AB group (all P < 0.05). In the AB group, an increase in interleukin - 6 immediately after the exercise at VT1 compared with baseline was found (P = 0.01).Conclusion: Individuals with SCI may have to perform physical exercise at a higher volume or energy expenditure than AB individuals to obtain similar anti-inflammatory benefits of acute exercise.Trial registration: Uniform Trial Number identifier: U1111-1232-8142.

Comparison Between Full-Body vs. Split-Body Resistance Exercise on the Brain-Derived Neurotrophic Factor and Immunometabolic Response

Lira, FS, Conrado de Freitas, M, Gerosa-Neto, J, Cholewa, JM, and Rossi, FE. Comparison between full-body vs. split-body resistance exercise on the brain-derived neurotrophic factor immunometabolic response. J Strength Cond Res 34(11): 3094-3102, 2020-Intense aerobic exercise seems to increase serum concentrations of brain-derived neurotrophic factor (BDNF) in conjunction with increasing lactate; however, less is known about the BDNF response to differing resistance exercise protocols. We hypothesized that full-body (FB) resistance exercise will elicit a greater increase in serum BDNF and lactate compared with split-body resistance exercise. Twelve recreationally resistance-trained men (age = 25.3 ± 5.9 years) performed 3 randomized trials of 18 sets of exercise: upper-body (UB), lower-body (LB), and FB conditions. Serum BDNF levels were assessed at rest, immediately Post-exercise, Post-1 hour, and Post-2 hours during recovery. Lactate concentration was evaluated at rest, after 9 sets, Post-exercise, Post-5, Post-10, and Post-30 minutes during recovery. In addition, interleukin (IL-6 and IL-10) and the IL-6/IL-10 ratio were calculated. Lactate concentration and total volume were greater in the FB condition compared with LB and UB (p < 0.05). For BDNF, effect sizes were largest in the LB (1.4), followed by the FB (0.75), and moderate to UB (0.33), although no significant differences were observed between conditions. There was a statistically significant relationship between lactate and BDNF only for LB condition (rho = 0.72; p = 0.013). There were a greater IL-10 Post-1 hour for FB condition compared with UB and LB (p < 0.001), and lower IL-6/IL-10 ratio in FB compared with UB (p < 0.001). Lower body induced a great BDNF response, and FB resistance exercise elicited a greater increase of serum cytokines than UB in trained men. We speculate that the volume of work performed by larger muscles has a larger influence on BDNF than overall volume.

Exercise intensity-dependent effects of arm and leg-cycling on cognitive performance

Physiological responses to arm and leg-cycling are different, which may influence psychological and biological mechanisms that influence post-exercise cognitive performance. The aim of this study was to determine the effects of maximal and submaximal (absolute and relative intensity matched) arm and leg-cycling on executive function. Thirteen males (age, 24.7 ± 5.0 years) initially undertook two incremental exercise tests to volitional exhaustion for arm-cycling (82 ± 18 W) and leg-cycling (243 ± 52 W) for the determination of maximal power output. Participants subsequently performed three 20-min constant load exercise trials: (1) arm-cycling at 50% of the ergometer-specific maximal power output (41 ± 9 W), (2) leg-cycling at 50% of the ergometer-specific maximal power output (122 ± 26 W), and (3) leg-cycling at the same absolute power output as the submaximal arm-cycling trial (41 ± 9 W). An executive function task was completed before, immediately after and 15-min after each exercise test. Exhaustive leg-cycling increased reaction time (p < 0.05, d = 1.17), while reaction time reduced following exhaustive arm-cycling (p < 0.05, d = -0.62). Improvements in reaction time were found after acute relative intensity arm (p < 0.05, d = -0.76) and leg-cycling (p < 0.05, d = -0.73), but not following leg-cycling at the same absolute intensity as arm-cycling (p > 0.05). Improvements in reaction time following arm-cycling were maintained for at least 15-min post exercise (p = 0.008, d = -0.73). Arm and leg-cycling performed at the same relative intensity elicit comparable improvements in cognitive performance. These findings suggest that individuals restricted to arm exercise possess a similar capacity to elicit an exercise-induced cognitive performance benefit.

Modality-specific training adaptations - do they lead to a dampened acute inflammatory response to exercise?

While adaptations to a short-term training program can dampen the acute inflammatory response to exercise, less is known about the influence of chronic modality-specific adaptations to training. This study compares the acute inflammatory response to upper- and lower-body interval exercise in individuals chronically trained in these respective modalities. Ninety minutes of interval exercise matched for relative power output on an arm-crank (ARM) and cycle ergometer (LEG) was performed by 8 trained paddlers and 8 trained cyclists. Blood samples were taken before and after exercise. Interleukin-6 (IL-6) concentrations were analysed in plasma, while the expression of intracellular heat shock protein 72 (iHsp72) was assessed in monocytes. IL-6 was increased following both modalities (fold change - ARM: 7.23 ± 3.56, p < 0.001; LEG: 9.03 ± 4.82, p < 0.001), in both groups (cyclists, p < 0.001; paddlers, p < 0.001), but the increase was smaller in ARM compared with LEG (time × modality, p < 0.001). ARM induced a smaller iHsp72 response compared with LEG (fold change - ARM: 1.07 ± 0.14, p = 0.102; LEG: 1.18 ± 0.14, p < 0.001; time × modality, p = 0.039). Following ARM, iHsp72 expression was increased in the cyclists only (fold change cyclists: 1.12 ± 0.11, p = 0.018; paddlers: 1.03 ± 0.17, p = 0.647), while iHsp72 expression following LEG was increased in both groups (fold change cyclists: 1.14 ± 0.15, p = 0.027; paddlers: 1.22 ± 0.13, p < 0.001). Taken together, the acute inflammatory response to lower-body interval exercise was larger compared with work-matched upper-body interval exercise. Moreover, adaptations to upper-body exercise training dampened the iHsp72 response to this modality. Therefore, exercise may be less effective in reducing chronic low-grade inflammation in individuals relying on their upper body, such as wheelchair users.

Exercise intensity and its impact on relationships between salivary immunoglobulin A, saliva flow rate and plasma cortisol concentration

Introduction

Salivary secretory immunoglobulin A (sIgA), saliva flow rate and plasma cortisol concentrations have been shown to be influenced by exercise, particularly the intensity exercise is performed at, and circadian variation. The autonomic nervous system partly regulates salivary secretion, but it is not yet known whether cortisol also explains some variation in salivary parameters.

Methods

Twelve moderately trained male individuals (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot {V}{{\text{O}}_2}$$\end{document}V˙O2_{peak legs}: 46.2 ± 6.8 mL·kg⁻¹·min⁻¹) performed three 45-min constant load exercise trials in the morning: arm cranking exercise at 60%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot {V}{{\text{O}}_2}$$\end{document}V˙O2_{peak arms}; moderate cycling at 60%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot {V}{{\text{O}}_2}$$\end{document}V˙O2_{peak legs}; and easy cycling at 60%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot {V}{{\text{O}}_2}$$\end{document}V˙O2_{peak arms}. Timed saliva samples and blood samples for plasma cortisol concentration determination were obtained before, post, 2 h post, and 4 h post-exercise. Saliva was collected in an additional resting trial at the same time points.

Results

At each time point for each exercise trial, negative correlations between cortisol and saliva flow rate (explaining 25 ± 17% of the variance, R² = 0.002–0.46) and positive correlations between cortisol and sIgA concentration (explaining 8 ± 8% of the variance R² = 0.002–0.24) were found. Saliva flow rate increased over time, whereas sIgA concentration and cortisol decreased over time for all trials (P < 0.05), there was no effect of time for sIgA secretion rate (P = 0.16).

Conclusion

These results show a relationship between cortisol and saliva flow rate, which directly impacts on the concentration of salivary analytes. This study further confirms circadian variations in salivary parameters which must be acknowledged when standardising salivary data collection.

Comparable Neutrophil Responses for Arm and Intensity-matched Leg Exercise

INTRODUCTION

Arm exercise is performed at lower absolute intensities than lower body exercise. This may impact on intensity-dependent neutrophil responses, and it is unknown whether individuals restricted to arm exercise experience the same changes in the neutrophil response as found for lower body exercise. Therefore, we aimed to investigate the importance of exercise modality and relative exercise intensity on the neutrophil response.

METHODS

Twelve moderately trained men performed three 45-min constant load exercise trials after determination of peak oxygen uptake for arm exercise (V˙O2peak arms) and cycling (V˙O2peak legs): 1) arm cranking exercise at 60% V˙O2peak arms, 2) moderate cycling at 60% V˙O2peak legs, and 3) easy cycling at 60% V˙O2peak arms.

RESULTS

Neutrophil numbers in the circulation increased for all exercise trials, but were significantly lower for easy cycling when compared with arm exercise (P = 0.009), mirroring the blunted increase in HR and epinephrine during easy cycling. For all trials, exercising HR explained some of the variation of the neutrophil number 2 h postexercise (R = 0.51-0.69), epinephrine explaining less of this variation (R = 0.21-0.34). The number of neutrophils expressing CXCR2 decreased in the recovery from exercise in all trials (P < 0.05).

CONCLUSIONS

Arm and leg exercise elicits the same neutrophil response when performed at the same relative intensity, implying that populations restricted to arm exercise might achieve a similar exercise induced neutrophil response as those performing lower body exercise. A likely explanation for this is the higher sympathetic activation and cardiac output for arm and relative intensity-matched leg exercise when compared with easy cycling, which is partly reflected in HR. This study further shows that the downregulation of CXCR2 may be implicated in exercise-induced neutrophilia.

A system model of the effects of exercise on plasma Interleukin-6 dynamics in healthy individuals: Role of skeletal muscle and adipose tissue

Interleukin-6 (IL-6) has been recently shown to play a central role in glucose homeostasis, since it stimulates the production and secretion of Glucagon-like Peptide-1 (GLP-1) from intestinal L-cells and pancreas, leading to an enhanced insulin response. In resting conditions, IL-6 is mainly produced by the adipose tissue whereas, during exercise, skeletal muscle contractions stimulate a marked IL-6 secretion as well. Available mathematical models describing the effects of exercise on glucose homeostasis, however, do not account for this IL-6 contribution. This study aimed at developing and validating a system model of exercise’s effects on plasma IL-6 dynamics in healthy humans, combining the contributions of both adipose tissue and skeletal muscle. A two-compartment description was adopted to model plasma IL-6 changes in response to oxygen uptake’s variation during an exercise bout. The free parameters of the model were estimated by means of a cross-validation procedure performed on four different datasets. A low coefficient of variation (<10%) was found for each parameter and the physiologically meaningful parameters were all consistent with literature data. Moreover, plasma IL-6 dynamics during exercise and post-exercise were consistent with literature data from exercise protocols differing in intensity, duration and modality. The model successfully emulated the physiological effects of exercise on plasma IL-6 levels and provided a reliable description of the role of skeletal muscle and adipose tissue on the dynamics of plasma IL-6. The system model here proposed is suitable to simulate IL-6 response to different exercise modalities. Its future integration with existing models of GLP-1-induced insulin secretion might provide a more reliable description of exercise’s effects on glucose homeostasis and hence support the definition of more tailored interventions for the treatment of type 2 diabetes.

Can intervals enhance the inflammatory response and enjoyment in upper-body exercise?

PURPOSE

To investigate the inflammatory and perceptual responses to three different forms of upper-body exercise.

METHODS

Twelve recreationally active, able-bodied males performed three work-matched arm-crank sessions in a randomised order: 30 min moderate-intensity continuous (CON), 30 min moderate-intensity with changes in cadence (CAD) and 20 min high-intensity interval training (HIIT). Blood samples were taken pre, post and 2-h post-exercise to determine plasma concentrations of interleukin (IL)-6 and IL-1ra. Perceptual responses pre, during and following the trials were assessed using the Feeling Scale, Felt Arousal Scale, Ratings of Perceived Exertion (RPE) and the Physical Activity Enjoyment Scale (PACES).

RESULTS

All trials were evenly effective in inducing an acute inflammatory response, indicated by similar increases in IL-6 after exercise and in IL-1ra at 2-h post exercise for all trials. More negative affect and higher RPE were reported during HIIT compared to CON and CAD, whereas PACES scores reported after exercise were higher for HIIT and CAD compared to CON.

CONCLUSIONS

When matched for external work, there was no difference in the inflammatory response to HIIT compared to moderate-intensity upper-body exercise. Although HIIT was (perceived as) more strenuous and affective responses were more negative during this mode, the higher ratings of enjoyment for both HIIT and CAD reported after exercise suggest that the inclusion of variation enhances enjoyment in upper-body exercise. As the fashion in which upper-body exercise is performed does not seem to influence the inflammatory response, it might be advised to prescribe varied exercise to enhance its enjoyment.

Increasing heat storage by wearing extra clothing during upper body exercise up-regulates heat shock protein 70 but does not modify the cytokine response

Plasma heat shock protein 70 (HSP70) concentrations rise during heat stress, which can independently induce cytokine production. Upper body exercise normally results in modest body temperature elevations. The aim of this study was to investigate the impacts of additional clothing on the body temperature, cytokine and HSP70 responses during this exercise modality. Thirteen males performed 45-min constant-load arm cranking at 63% maximum aerobic power (62 ± 7%V̇O_2peak) in either a non-permeable whole-body suit (intervention, INT) or shorts and T-shirt (control, CON). Exercise resulted in a significant increase of IL-6 and IL-1ra plasma concentrations (P < 0.001), with no difference between conditions (P > 0.19). The increase in HSP70 from pre to post was only significant for INT (0.12 ± 0.11ng∙mL^-1, P < 0.01 vs. 0.04 ± 0.18 ng∙mL^-1, P = 0.77). Immediately following exercise, T_core was elevated by 0.46 ± 0.29 (INT) and 0.37 ± 0.23ºC (CON), respectively (P < 0.01), with no difference between conditions (P = 0.16). The rise in mean T_skin (2.88 ± 0.50 and 0.30 ± 0.89ºC, respectively) and maximum heat storage (3.24 ± 1.08 and 1.20 ± 1.04 J∙g^-1, respectively) was higher during INT (P < 0.01). Despite large differences in heat storage between conditions, the HSP70 elevations during INT, even though significant, were very modest. Possibly, the T_core elevations were too low to induce a more pronounced HSP70 response to ultimately affect cytokine production.