Feeling state responses to acute exercise of high and low intensity

Acute Physiological and Perceptual Responses to Whole-Body High-Intensity Interval Training Compared with Equipment-Based Interval and Continuous Training

Low-volume, time-efficient high-intensity interval training (HIIT), which involves whole-body (WB) callisthenics exercises, has gained worldwide popularity in recent years. However, the physiological and perceptual impact of WB-HIIT in comparison to specialised, equipment-based training is relatively less studied. This study compared the acute physiological and perceptual responses to a single session of WB-HIIT, ergometer-based HIIT (ERG-HIIT) and conventional moderate-intensity continuous training (MICT). Fourteen physically inactive adults (age: 28.4 ± 6.5 years, VO2peak: 31.0 ± 6.2 mL· kg-1· min-1) underwent three main trials (WB-HIIT: 12 x 30-s high-intensity callisthenics workout; ERG: HIIT: 12 x 30-s high-intensity cycling bouts; MICT: 30-min cycling at 50% peak power output) in a randomized cross-over order 3-7 days apart. The mean session heart rate (HR) and perceived exertion were comparable across all three protocols (p > 0.05). WB-HIIT attained a similar peak HR (87.4 ± 9.4 %HRmax) as that of ERG-HIIT (83.0 ± 8.6 %HRmax), and significantly greater than that of MICT (78.7 ± 5.5 %HRmax, p = 0.001). However, WB-HIIT induced significantly higher blood lactate levels (7.2 ± 1.8 mmol/L) compared to both ERG-HIIT (5.1 ± 1.3 mmol/L, p < 0.05) and MICT (3.1 ± 1.5 mmol/L, p < 0.001). The participants reported higher self-efficacy and greater enjoyment with WB-HIIT compared to MICT (p < 0.05). The mean HR and perceived exertion responses to WB-HIIT are comparable to those of equipment-based HIIT and MICT; however, WB-HIIT results in greater metabolic strain than both other modalities. Despite this, the overall perceptual responses to WB-HIIT are positive, suggesting that it could be a viable exercise alternative, especially for individuals with limited exercise time and restricted access to facilities and equipment.

Dose-response effects of acute exercise intensity on state anxiety among women with depression

Anxiety is common in people with major depressive disorder (MDD), yet the anxiolytic effects of acute exercise in MDD are unknown. The purpose of this analysis was to determine a potentially optimal acute exercise intensity for reducing state anxiety in women with MDD, the duration of the response, and the potential influences of depression severity and preferred-intensity exercise. Using a within-subject, randomized, counter-balanced design, 24 participants completed five separate visits including 20  min of steady-state bicycling at prescribed (via RPE) light, moderate, or hard intensities, a preferred/self-selected session, or a quiet rest (QR) session. State anxiety was measured via the State-Trait Anxiety Inventory (STAI-Y1) and anxiety visual analog scale (VAS) at pre-, immediately (VAS only), 10  min, and 30  min post-exercise. Depression was measured via the Beck Depression Inventory (BDI-II) pre-exercise. Moderate exercise resulted in a moderate state anxiety reduction compared to QR 10 min (STAI-Y1: g = 0.59, p_adj = 0.040) and 30 min post-exercise (STAI-Y1: g = 0.61, p_adj = 0.032). Pairwise differences indicated each exercise session decreased state anxiety pre to 10 min and 30 min post-exercise (all p_adj < 0.05) for the STAI-Y1, and for moderate and hard exercise from pre to each time point post-exercise (all p_adj < 0.05) for the VAS. Depression severity was associated with state anxiety (p < 0.01) but did not influence the overall results. Prescribed moderate intensity exercise led to greater reductions in state anxiety compared to preferred at 30 m (STAI-Y1: g = 0.43, p = 0.04). These findings suggest steady-state prescribed moderate exercise reduces state anxiety in women with MDD for at least 30 min following exercise regardless of their depression severity.

The Effect of Aerobic Fitness on Psychological, Attentional and Physiological Responses during a Tabata High-Intensity Interval Training Session in Healthy Young Women

The current study examines the effects of a Tabata high-intensity interval training (HIIT) session on affective, cognitive and physiological indicators in women of different fitness levels. A total of 28 adult women (aged 24.2 ± 1.5 years) completed a 20 m shuttle run test and were then assigned to higher fitness and lower fitness groups (HF and LF, n = 14 each) according to their predicted aerobic power. On a separate occasion, participants completed a 30 min Tabata workout (six 4 min rounds separated by 1 min passive rest). Each round included eight exercises (20 s exercise and 10 s rest). Affective, physiological and cognitive responses were assessed prior to, during and after the protocol. Heart rate and blood lactate concentration increased similarly in both groups over time throughout the workout (p < 0.001). Total Mood Disturbance was higher for LF (111.4 ± 15.7) vs. HF (102.9 ± 11.7) (p = 0.48), vigor showed a level by time interaction of p = 0.006 and Activation−Deactivation Adjective Check List factors deteriorated over time (p < 0.001). The Concentration Grid Test was better overall for HF (10.5 ± 3.6) vs. LF (8.6 ± 3.6) (p = 0.05). The Feeling Scale and Rating of Perceived Exertion worsened similarly in both groups over time (p = 0.002 and p < 0.001, respectively). Positive and negative affect and arousal did not differ between groups or change over time (p > 0.05). These results show that, despite the different levels of aerobic fitness, physiological, metabolic, perceptual and affective responses were similar in the two groups of women during a 30 min Tabata session. This may imply that affective responses during this type of HIIT are independent of aerobic fitness.

Psychological Responses to Progressive Exercise Until Voluntary Exhaustion: A Study of Adolescent Male Basketball Players

The affective experience during and after exercise helps determine motivation, commitment, and adherence to sports. Choice reaction time (RT) is critical in decision-making and sports performance. In this within-subjects laboratory experiment, we scrutinized core affect and choice RT in 18 male adolescent basketball players during exercise sessions performed to voluntary exhaustion and during a control condition. The adolescents performed choice RT tasks in one of two exercise conditions and in the control session. Participants' feeling states differed between exercise and control sessions and decreased slightly even after moderate exercise intensity. Core affect also declined as the workload increased, but it remained pleasant-activated in all conditions. The RT errors increased at the peak exercise intensity. These results suggest that while high-intensity training might negatively affect young athletes' feeling states and impair their decision-making, their core affect remained positive, with large inter-individual variability. We discuss the practical implications of these results in adolescents' sports.

Affective Responses during High-Intensity Interval Exercise Compared with Moderate-Intensity Continuous Exercise in Inactive Women

This study aimed to investigate the effects of an acute bout of high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) on affective responses in inactive women. Thirty women with normal body mass index (BMI) and 30 women with BMI ≥ 24 kg/m² participated in the study. All participants completed a graded exercise test and performed two exercise sessions (HIIE and MICE) in random order. Affective responses were assessed during and after each exercise session, using the rating of perceived exertion (RPE), Self-Assessment-Manikin (SAM), and Subjective Exercise Experience Scale (SEES). The results showed that the RPE scores were significantly higher in HIIE than in MICE. HIIE resulted in significantly lower pleasure scores using the SAM while arousal and dominance scores were significantly higher with HIIE compared to MICE. Positive well-being scores using the SEES were significantly lower with HIIE and both psychological distress and fatigue scores were significantly higher with HIIE. The results showed that affective responses with MICE were more positive than with HIIE, but no differences were found between normal and overweight/obese women. Based on these results, MICE may be a more acceptable exercise program for inactive women regardless of their weight status.

Acute Cardiopulmonary Response to Interval and Continuous Exercise in Older Adults: A Randomized Crossover Study

ABSTRACT

Linares, AM, Goncin, N, Stuckey, M, Burgomaster, KA, and Dogra, S. Acute cardiopulmonary response to interval and continuous exercise in older adults: a randomized crossover study. J Strength Cond Res XX(X): 000-000, 2020-The purpose of this study was to compare the cardiopulmonary response with different exercise protocols in healthy older adults. Subjects (n = 30; 15 women, age: 69.6 ± 6.2 years) completed an exercise test (MAX) on a cycle ergometer to determine maximal oxygen consumption (V[Combining Dot Above]O2max) and peak power output (PPO). Exercise sessions were randomized: high-intensity interval exercise (HIIE, 1 minute 90% PPO followed by 1 minute 10% PPO, ×10), moderate-intensity continuous exercise (MOD, 20 minutes at 50% PPO), and sprint-interval exercise (SPRT, 20 seconds "all-out" sprints followed by 2 minutes at 50 W, ×3). V[Combining Dot Above]O2max was highest during MAX in men (MAX: 28.2 ± 6.3; MOD: 22.6 ± 4.5; HIIE: 26.7 ± 5.7; SPRT: 26.0 ± 4.3; F(2.1) = 28.6, p = 0.0001, = 0.67), whereas similar peaks were observed between HIIE, SPRT, and MAX in women (MAX: 21.9 ± 6.1; MOD: 18.9 ± 4.5; HIIE: 21.6 ± 5.3; SPRT: 21.7 ± 3.9; F(2.2) = 10.2, p = 0.0001, = 0.42). The peak heart rate (b·min-1) was similar across all exercise sessions in both men (MAX: 148.1 ± 17.1; MOD: 132.6 ± 21.8; HIIE: 144.9 ± 16.6; SPRT: 148.6 ± 14.2; F(1.9) = 9.1, p = 0.001, = 0.41) and women (MAX: 148.1 ± 13.1; MOD: 136.3 ± 18.2; HIIE: 147.0 ± 16.4; SPRT: 148.5 ± 18.0; F(2.0) = 5.3, p = 0.011, = 0.27). The %V[Combining Dot Above]O2 at which sessions were performed varied significantly across individual subjects. In conclusion, older women work at near maximal V[Combining Dot Above]O2 when performing HIIE and SPRT; this has implications for exercise testing and prescription protocols in older adults.

An Exercise Prescription for COVID-19 Pandemic

COVID-19 is an alarming public health concern worldwide. COVID-19 is highly contagious and has no approved treatment or vaccine yet. Therefore, the best strategy is prevention. Studies have shown that a healthy lifestyle, regular exercise, balanced eating, and quality sleep are the key elements for protection from this disease. We are going through a distressful period as a nation and as the human race in general. We need to manage this period in the best way possible in physiological and psychological terms. Physical activity is one of the major steps in managing this period in a healthy way. Individuals should be provided information about exercise so that they can perform correct physical activities within their means. This article presents an exercise prescription that can be followed in the days of the COVID-19 pandemic.

Exercise and Coronary Heart Disease

Coronary artery disease (CAD) can be obstructive or nonobstructive. Patients with nonobstructive and stable angina pectoris are usually women. Nonobstructive CAD is caused by endothelial dysfunction at the microvascular level, such as cardiac syndrome X and coronary slow flow syndrome. Even if coronary anatomy is nonobstructive, the presence of myocardial ischemia is a major determinant for the exercise program. CAD is a chronic inflammatory disease, and the progression of the disease can lead to a rapid change in the functional capacity of CAD patients. Exercise training is a major component of cardiac rehabilitation and reduces cardiovascular mortality, morbidity, and rehospitalization as well as improves psychological stress and controls risk factors of CAD, such as diabetes mellitus, hypertension, and obesity. It is possible that the quality of life of patients with CAD can be improved by using appropriate exercise therapy. However, the exercise programs among CAD patients are highly underutilized. This chapter will summarize the research progress of exercise in the prevention and treatment of CAD as well as how to create safe exercise programs and the importance of exercise for patients with CAD. In addition, exercise training has fundamental beneficial effects on ischemic and nonischemic heart failure.

Special Issue - Therapeutic Benefits of Physical Activity for Mood: A Systematic Review on the Effects of Exercise Intensity, Duration, and Modality

In contemporary society, people experience considerable stress in their daily lives. Therefore, developing effective approaches and convenient means to cope with their mood problems is important nowadays. Physical activity has been consistently reported as a cost-effective way to improve physical fitness, prevent mental illnesses, and alleviate mood problems. In this systematic review, the effects of exercise intensity, duration, and modality on mood change are discussed. Results show that moderate-intensity anaerobic exercise is associated with greater mood improvements. The relationship between exercise duration and mood change is non-linear; A regime of 10- to 30-minute exercise is sufficient for mood improvements. For exercise modality, anaerobic exercise improves mood, but the efficacy of aerobic and mindfulness-related exercises remains to be further examined. In addition to the systematic review of potential moderators, a narrative review of psychological and neurophysiological theories of exercise effects on mood is provided; we have highlighted the central role of neuroplasticity in integrating the two classes of theories. An adoption of neuroimaging techniques in future research is critical to reveal the mechanisms underpinning the therapeutic influence of physical activity on affective responses. Some future research directions are also raised.

Age-specific affective responses and self-efficacy to acute high-intensity interval training and continuous exercise in insufficiently active young and middle-aged men

Background/objective

High-intensity interval training (HIIT) has been recognized as an emerging trend in public health promotion, but its age-specific differences in psycho-perceptual responses have yet to be investigated. This study compared the psycho-perceptual responses after a single session of HIIT versus moderate-intensity continuous exercise (MICE) and vigorous-intensity continuous exercise (VICE) in twelve young and twelve middle-aged insufficiently active males respectively.

Methods

Using a randomized cross-over design, participants undertook three main trials consisting of: HIIT (10 x 1-min run at 100% VO_2max interspersed with 1-min active recovery), MICE (40-min run at 65% VO_2max) and VICE (20-min run at 80% VO_2max). Affective responses, self-efficacy and exercise preference were assessed for each trial.

Results

Both HIIT and VICE showed more positive in-task affective responses than MICE in young adults, while middle-aged adults reported more positive responses in both HIIT and MICE than in VICE. However, middle-aged adults displayed significantly lower exercise task self-efficacy scores towards HIIT (42.7 ± 25.3) and VICE (49.2 ± 23.9) than MICE (63.4 ± 18.3, both P < 0.01). Additionally, only 17% of participants in the middle-aged group reported a preference to engage in HIIT as opposed to either MICE (50%) and VICE (33%).

Conclusion

Our finding revealed distinct affective and self-efficacy responses to acute HIIT versus both MICE and VICE in the two age groups which assists in our understanding of how individuals in various age populations perceive HIIT. This information will assist in the design and implementation of effective exercise programs for public health, especially for insufficiently active individuals.

The effects of upper and lower limb exercise on the microvascular reactivity in limited cutaneous systemic sclerosis patients

BACKGROUND

Aerobic exercise in general and high-intensity interval training (HIIT) specifically is known to improve vascular function in a range of clinical conditions. HIIT in particular has demonstrated improvements in clinical outcomes, in conditions that have a strong macroangiopathic component. Nevertheless, the effect of HIIT on microcirculation in systemic sclerosis (SSc) patients is yet to be investigated. Therefore, the purpose of the study was to compare the effects of two HIIT protocols (cycle and arm cranking) on the microcirculation of the digital area in SSc patients.

METHODS

Thirty-four limited cutaneous SSc patients (65.3 ± 11.6 years old) were randomly allocated in three groups (cycling, arm cranking and control group). The exercise groups underwent a 12- week exercise program twice per week. All patients performed the baseline and post-exercise intervention measurements where physical fitness, functional ability, transcutaneous oxygen tension (ΔTcpO2), body composition and quality of life were assessed. Endothelial-dependent as well as -independent vasodilation were assessed in the middle and index fingers using LDF and incremental doses of acetylcholine (ACh) and sodium nitroprusside (SNP). Cutaneous flux data were expressed as cutaneous vascular conductance (CVC).

RESULTS

Peak oxygen uptake increased in both exercise groups (p < 0.01, d = 1.36). ΔTcpO2 demonstrated an increase in the arm-cranking group only, with a large effect, but not found statistically significant,(p = 0.59, d = 0.93). Endothelial-dependent vasodilation improvement was greater in the arm-cranking (p < 0.05, d = 1.07) in comparison to other groups. Both exercise groups improved life satisfaction (p < 0.001) as well as reduced discomfort and pain due to Raynaud's phenomenon (p < 0.05). Arm cranking seems to be the preferred mode of exercise for study participants as compared to cycling (p < 0.05). No changes were observed in the body composition or the functional ability in both exercise groups.

CONCLUSIONS

Our results suggest that arm cranking has the potential to improve the microvascular endothelial function in SSc patients. Also notably, our recommended training dose (e.g., a 12-week HIIT program, twice per week), appeared to be sufficient and tolerable for this population. Future research should focus on exploring the feasibility of a combined exercise such as aerobic and resistance training by assessing individual's experience and the quality of life in SSc patients.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT number): NCT03058887 , February 23, 2017.

The relationships between exercise and affective states: a naturalistic, longitudinal study of recreational runners

BACKGROUND

Although people generally feel more positive and more energetic in the aftermath of exercise than before, longitudinal research on how exercise relates to within-person fluctuations in affect over the course of everyday life is still relatively limited. One constraint on doing such research is the need to provide participants with accelerometers to objectively record their exercise, and pagers to capture affective reports.

AIMS

We aimed to develop a methodology for studying affect and exercise using only technology that participants already possess, namely GPS running watches and smartphones. Using this methodology, we aimed to characterize within-individual fluctuations in affective valence and arousal in relation to bouts of exercise, and explore possible moderators of these fluctuations.

METHODS

We recruited a sample of 38 recreational runners. Participants provided daily affective reports for six weeks using their smartphones. Information on their runs was harvested from their own GPS devices via an online platform for athletes.

RESULTS

Average valence and arousal were higher on days when the person had run than on the next day, and higher the day after a run than on the days after that. Over the course of the day of a run, valence and arousal declined significantly as the time since the run increased. Physically fitter participants had more positive valence overall, and this was particularly true when they had not run recently. There was some evidence of higher-dose (i.e., longer and faster) runs being associated with lower arousal on the next and subsequent days. Gender did not moderate associations between running and valence or arousal.

DISCUSSION

Our study demonstrated the potential for studying the associations between affect and exercise in a way that is precise, undemanding for participants, and convenient for researchers, using technologies that participants already own and use.

Psychological Responses to Acute Aerobic, Resistance, or Combined Exercise in Healthy and Overweight Individuals: A Systematic Review

INTRODUCTION

Psychological distress and depression are risk factors for cardiovascular disease (CVD). As such, a reduction in psychological distress and increase in positive well-being may be important to reduce the risk for future development of CVD. Exercise training may be a good strategy to prevent and assist in the management of psychological disorders. The psychological effects of the initial exercise sessions may be important to increase exercise adherence. The aims of this systematic review were (a) to examine whether acute aerobic, resistance, or a combination of the 2 exercises improves psychological well-being and reduces psychological distress in individuals with healthy weight and those who are overweight/obese but free from psychological disorders, and (b) if so, to examine which form of exercise might yield superior results.

METHODS

The online database PubMed was searched for articles using the PICO (patient, intervention, comparison, and outcome) framework for finding scientific journals based on key terms.

RESULTS

Forty-two exercise studies met the inclusion criteria. A total of 2187 participants were included (age: 18-64 years, body mass index [BMI]: 21-39 kg/m2). Only 6 studies included participants with a BMI in the overweight/obese classification. Thirty-seven studies included aerobic exercise, 2 included resistance exercise, 1 used a combination of aerobic and resistance, and 2 compared the effects of acute aerobic exercise versus the effects of acute resistance exercise. The main findings of the review were that acute aerobic exercise improves positive well-being and have the potential to reduce psychological distress and could help reduce the risks of future CVD. However, due to the limited number of studies, it is still unclear which form of exercise yields superior psychological benefits.

CONCLUSIONS

Obese, overweight, and healthy weight individuals can exhibit psychological benefits from exercise in a single acute exercise session, and these positive benefits of exercise should be used by health professionals as a tool to increase long-term participation in exercise in these populations.

Affective responses after different intensities of exercise in patients with traumatic brain injury

Background: Patients with traumatic brain injury (TBI) usually have mood and anxiety symptoms secondary to their brain injury. Exercise may be a cost-effective intervention for the regulation of the affective responses of this population. However, there are no studies evaluating the effects of exercise or the optimal intensity of exercise for this clinical group.

Methods: Twelve male patients with moderate or severe TBI [mean age of 31.83 and SD of 9.53] and 12 age- and gender-matched healthy volunteers [mean age of 30.58 and SD of 9.53] participated in two sessions of exercise of high and moderate-intensity. Anxiety and mood was evaluated, and subjective assessment of experience pre- and post-exercise was assessed. A mixed between and within-subjects general linear model (GLM) analysis was conducted to compare groups [TBI, control] over condition [baseline, session 1, session 2] allowing for group by condition interaction to be determined. Planned comparisons were also conducted to test study hypotheses.

Results: Although no group by condition interaction was observed, planned comparisons indicated that baseline differences between patients and controls in anxiety (Cohens’ d = 1.80), tension (d = 1.31), depression (d = 1.18), anger (d = 1.08), confusion (d = 1.70), psychological distress (d = 1.28), and physical symptoms (d = 1.42) disappear after one session of exercise, independently of the intensity of exercise.

Conclusion: A single-section of exercise, regardless of exercise intensity, had a positive effect on the affective responses of patients with TBI both by increasing positive valence feelings and decreasing negative ones. Exercise can be an easily accessible intervention that may alleviate depressive symptoms related to brain injury.

Where does HIT fit? An examination of the affective response to high-intensity intervals in comparison to continuous moderate- and continuous vigorous-intensity exercise in the exercise intensity-affect continuum

Affect experienced during an exercise session is purported to predict future exercise behaviour. Compared to continuous moderate-intensity exercise (CMI), the affective response to continuous vigorous-intensity exercise (CVI) has consistently been shown to be more aversive. The affective response, and overall tolerability to high-intensity interval training (HIT), is less studied. To date, there has yet to be a comparison between HIT, CVI, and CMI. The purpose of this study was to compare the tolerability and affective responses during HIT to CVI and CMI. This study utilized a repeated measures, randomized, counter-balanced design. Forty-four participants visited the laboratory on four occasions. Baseline fitness testing was conducted to establish peak power output in Watts (W peak). Three subsequent visits involved a single bout of a) HIT, corresponding to 1-minute at ∼ 100% W peak and 1-minute at ∼ 20% W peak for 20 minutes, b) CMI, corresponding to ∼ 40% W peak for 40 minutes, and c) CVI, corresponding to ∼ 80% W peak for 20 minutes. The order of the sessions was randomized. Affective responses were measured before, during and after each session. Task self-efficacy, intentions, enjoyment and preference were measured after sessions. Participants reported greater enjoyment of HIT as compared to CMI and CVI, with over 50% of participants reporting a preference to engage in HIT as opposed to either CMI or CVI. HIT was considered more pleasurable than CVI after exercise, but less pleasurable than CMI at these times. Despite this participants reported being just as confident to engage in HIT as they were CMI, but less confident to engage in CVI. This study highlights the utility of HIT in inactive individuals, and suggests that it may be a viable alternative to traditionally prescribed continuous modalities of exercise for promoting self-efficacy and enjoyment of exercise.

Influence of Affective Changes on Behavioral and Cognitive Performances After Acute Bout of Exhaustive Exercise

The present study was conducted to evaluate the influence of acute, exhaustive, exercise on affective responses (affective valence and activation) and behavioral and cognitive performances in medical students using circumplex model, reaction time (RT), and P300, respectively. Twelve healthy, untrained, male medical students participated in self-controlled, counterbalanced trial conducted over two sessions: baseline and exercise. In the baseline session, recordings of auditory reaction time (ART), visual RT (VRT), and P300 latency and amplitude (using acoustic “oddball” paradigm) were taken at the end of 15 min seated rest. Exercise session comprised of continuous maximal graded incremental exercise until volitional exhaustion, on a computer-based motorized treadmill and recordings done after heart rate returned to within +10% of pre-exercise values. Perceived exertion, affective valence, and activation were assessed pre-exercise, during (30 s before the end of each stage), and post-exercise (immediately, 5 and 10 min after) by Borg’s scale, feeling scale (FS), and felt-arousal scale (FAS), respectively. There was marked variability in individual affective responses to a single bout of exhaustive exercise with few subjects showing activated pleasure (Energetic Arousal) and others showing activated displeasure (Tense arousal). The results further indicated an overall improvement in behavioral (as evidenced by the decrease in ART and VRT) and cognitive performances (as evidenced by increase in the P300 amplitude and decrease in the P300 latency) in medical students in the exercise session relative to the baseline session despite bidirectional shifts in valence suggesting that interdependent neural systems might mediate these effects.

Exogenously applied muscle metabolites synergistically evoke sensations of muscle fatigue and pain in human subjects

NEW FINDINGS

What is the central question of this study? Can physiological concentrations of metabolite combinations evoke sensations of fatigue and pain when injected into skeletal muscle? If so, what sensations are evoked? What is the main finding and its importance? Low concentrations of protons, lactate and ATP evoked sensations related to fatigue. Higher concentrations of these metabolites evoked pain. Single metabolites evoked no sensations. This suggests that the combination of an ASIC receptor and a purinergic P2X receptor is required for signalling fatigue and pain. The results also suggest that two types of sensory neurons encode metabolites; one detects low concentrations of metabolites and signals sensations of fatigue, whereas the other detects higher levels of metabolites and signals ache and hot. The perception of fatigue is common in many disease states; however, the mechanisms of sensory muscle fatigue are not understood. In mice, rats and cats, muscle afferents signal metabolite production in skeletal muscle using a complex of ASIC, P2X and TRPV1 receptors. Endogenous muscle agonists for these receptors are combinations of protons, lactate and ATP. Here we applied physiological concentrations of these agonists to muscle interstitium in human subjects to determine whether this combination could activate sensations and, if so, to determine how the subjects described these sensations. Ten volunteers received infusions (0.2 ml over 30 s) containing protons, lactate and ATP under the fascia of a thumb muscle, abductor pollicis brevis. Infusion of individual metabolites at maximal amounts evoked no fatigue or pain. Metabolite combinations found in resting muscles (pH 7.4 + 300 nm ATP + 1 mm lactate) also evoked no sensation. The infusion of a metabolite combination found in muscle during moderate endurance exercise (pH 7.3 + 400 nm ATP + 5 mm lactate) produced significant fatigue sensations. Infusion of a metabolite combination associated with vigorous exercise (pH 7.2 + 500 nm ATP + 10 mm lactate) produced stronger sensations of fatigue and some ache. Higher levels of metabolites (as found with ischaemic exercise) caused more ache but no additional fatigue sensation. Thus, in a dose-dependent manner, intramuscular infusion of combinations of protons, lactate and ATP leads to fatigue sensation and eventually pain, probably through activation of ASIC, P2X and TRPV1 receptors. This is the first demonstration in humans that metabolites normally produced by exercise act in combination to activate sensory neurons that signal sensations of fatigue and muscle pain.

Feasibility and preliminary efficacy of high intensity interval training in type 2 diabetes

AIMS

To compare the feasibility of high intensity interval exercise (HI-IE) versus moderate intensity continuous exercise (MI-CE) in patients with type 2 diabetes (T2D), and to investigate the preliminary efficacy of HI-IE and MI-CE for improving glycated hemoglobin A1c (HbA1c) and body composition.

METHODS

Individuals with T2D were recruited and randomly assigned to HI-IE and MI-CE. Exercise training was performed 5 days per week for 12 weeks. Recruitment, retention, adherence, feeling states and self-efficacy were analyzed for feasibility. Changes in HbA1c and percent body fat from baseline were investigated at 12 weeks to determine the preliminary efficacy.

RESULTS

Of 126 participants showing interest to join the study, 15 individuals were randomized and completed the program. No participants dropped out from the study after enrollment. Adherence rates were high and did not differ between HI-IE and MI-CE (p>0.05; >97.2% of the eligible exercise sessions for both groups). Feeling states and self-efficacy did not differ between the groups. Percent trunk fat decreased in both HI-IE and MI-CE (p=0.007 and 0.085, respectively). Total percent body fat, percent leg fat, and subcutaneous fat width were significantly reduced in both groups (p<0.05), whereas HbA1c did not change from baseline (p>0.05). The degree of improvement was similar between the interventions (p>0.05).

CONCLUSION

In individuals with T2D, implementing a 12-week structured HI-IE training can be as feasible as MI-CE training. Both interventions are equally effective in lowering total body fat but have little impact on HbA1c in relatively well controlled participants with T2D.

The pleasure and displeasure people feel when they exercise at different intensities: decennial update and progress towards a tripartite rationale for exercise intensity prescription

The public health problem of physical inactivity has proven resistant to research efforts aimed at elucidating its causes and interventions designed to alter its course. Thus, in most industrialized countries, the majority of the population is physically inactive or inadequately active. Most theoretical models of exercise behaviour assume that the decision to engage in exercise is based on cognitive factors (e.g. weighing pros and cons, appraising personal capabilities, evaluating sources of support). Another, still-under-appreciated, possibility is that these decisions are influenced by affective variables, such as whether previous exercise experiences were associated with pleasure or displeasure. This review examines 33 articles published from 1999 to 2009 on the relationship between exercise intensity and affective responses. Unlike 31 studies that were published until 1998 and were examined in a 1999 review, these more recent studies have provided evidence of a relation between the intensity of exercise and affective responses. Pleasure is reduced mainly above the ventilatory or lactate threshold or the onset of blood lactate accumulation. There are pleasant changes at sub-threshold intensities for most individuals, large inter-individual variability close to the ventilatory or lactate threshold and homogeneously negative changes at supra-threshold intensities. When the intensity is self-selected, rather than imposed, it appears to foster greater tolerance to higher intensity levels. The evidence of a dose-response relation between exercise intensity and affect sets the stage for a reconsideration of the rationale behind current guidelines for exercise intensity prescription. Besides effectiveness and safety, it is becoming increasingly clear that the guidelines should take into account whether a certain level of exercise intensity would be likely to cause increases or decreases in pleasure.

Affective and self-efficacy responses to acute aerobic exercise in sedentary older and younger adults

This study examined the psychological responses to an acute bout of aerobic exercise in sedentary older and younger adults. Eighteen young (mean age 24 years) and 15 older adults (mean age 64 years) completed a 20-min bout of stationary cycling at 65% of VO2peak. Affective responses were assessed before, during, and immediately after exercise. Participants'exercise self-efficacy beliefs were assessed before and immediately after exercise. Both groups reported reduced pleasant feeling states and self-efficacy and increased physical exhaustion in response to acute exercise. Older adults also demonstrated a significant decrease in revitalization during and after cycling. Correlation analyses revealed that self-efficacy was related to feelings of fatigue during exercise and postexercise feelings of energy and fatigue. Both groups reported negative shifts in affect and self-efficacy during and 5 min after cycling.Acute affective and self-efficacy responses might influence one's motivation to adopt and maintain regular physical activity. The relationship between these acute responses and physical activity behavior across the life span warrants future inquiry.

Physical activity and mental health: the association between exercise and mood

Physical activity is an important public health tool used in the treatment and prevention of various physical diseases, as well as in the treatment of some psychiatric diseases such as depressive and anxiety disorders. However, studies have shown that in addition to its beneficial effects, physical activity can also be associated with impaired mental health, being related to disturbances like "excessive exercise" and "overtraining syndrome". Although the number of reports of the effects of physical activity on mental health is steadily increasing, these studies have not yet identified the mechanisms involved in the benefits and dangers to mental health associated with exercise. This article reviews the information available regarding the relationship between physical activity and mental health, specifically addressing the association between exercise and mood.