Effect of hand cooling on body temperature, cardiovascular and perceptual responses during recumbent cycling in a hot environment

The purpose of this study was to quantify physiological and perceptual responses to hand immersion in water during recumbent cycling in a hot environment. Seven physically active males (body mass 79.8 ± 6.3 kg; stature 182 ± 5 cm; age 23 ± 3 years) immersed their hands in 8, 14 and 34°C water whilst cycling at an intensity (W) equivalent to 50% (Formula presented.)O2peak for 60 min in an environmental chamber (35°C, 50% relative humidity). 8 and 14°C water attenuated an increase in body temperature, and lowered cardiorespiratory and skin blood flow demands. These effects were considered to be practically beneficial (standardised effect size > 0.20). There was a tendency for 8 and 14°C to extend exercise duration versus 34°C (>7%). Heart rate, intestinal, mean skin and mean body temperature were less in 8°C compared to 14°C; these differences were considered practically beneficial. Augmented heat loss at the palm-water surface might enable cooler blood to return to the body and limit physiological strain. These findings provide a mechanistic basis for continuous hand cooling and indicate that endurance exercise in hot environments could be improved using this method. Future research should investigate its effectiveness during cycling and running performanc

Aging and aerobic fitness affect the contribution of noradrenergic sympathetic nerves to the rapid cutaneous vasodilator response to local heating

Sedentary aging results in a diminished rapid cutaneous vasodilator response to local heating. We investigated whether this diminished response was due to altered contributions of noradrenergic sympathetic nerves; assessing 1) the age-related decline and, 2) the effect of aerobic fitness. We measured skin blood flow (SkBF)(laser-Doppler flowmetry) in young (24±1 yr) and older (64±1 yr) endurance-trained and sedentary men (n=7 per group) at baseline and during 35 min of local skin heating to 42 °C at three forearm sites: 1) untreated; 2) bretylium tosylate (BT), preventing neurotransmitter release from noradrenergic sympathetic nerves; and 3) yohimbine and propranolol (YP), antagonising α- and β-adrenergic receptors. SkBF was converted to cutaneous vascular conductance (CVC) (SkBF/mean arterial pressure) and normalized to maximal CVC (%CVCmax) achieved by skin heating to 44 °C. Pharmacological agents were administered using microdialysis. In the young trained, the rapid vasodilator response was reduced at the BT and YP sites (P0.05) but treatment with BT did (P>0.05). Neither BT nor YP treatments affected the rapid vasodilator response in the older sedentary group (P>0.05). These data suggest that the age-related reduction in the rapid vasodilator response is due to an impairment of sympathetic-dependent mechanisms, which can be partly attenuated with habitual aerobic exercise. Rapid vasodilation involves noradrenergic neurotransmitters in young trained men, and non-adrenergic sympathetic cotransmitters (e.g., neuropeptide Y) in young sedentary and older trained men, possibly as a compensatory mechanism. Finally, in older sedentary men, the rapid vasodilation appears not to involve the sympathetic system

Effect of age on cutaneous vasomotor responses during local skin heating

This study examined the effect of ageing on the low-frequency oscillations (vasomotion) of skin blood flow in response to local heating (LH). Skin blood flow was assessed by laser-Doppler flowmetry on the forearm at rest (33 °C) and in response to LH of the skin to both 42 °C and 44 °C in 14 young (24 ± 1 years) and 14 older (64 ± 1 years) participants. Vasomotion was analyzed using a wavelet transform to investigate power of the frequency intervals associated with endothelial, neural, myogenic, respiratory, and cardiac activities of the laser-Doppler signal. Laser-Doppler flux increased in both groups with LH (both d > 1.8, p 1.2, p 0.9, p 0.7), myogenic (d = 0.3, p > 0.7), respiratory (d = 0.4, p > 0.6), and cardiac (d = 0.1, p > 0.7) frequency intervals. These data indicate that LH increases cutaneous endothelial and myogenic activity, while decreasing neural activity. Furthermore, ageing reduces the increase in cutaneous endothelial activity in response to LH

Practical Cooling Strategies During Continuous Exercise in Hot Environments: A Systematic Review and Meta-Analysis

Background Performing exercise in thermally stressful environments impairs exercise capacity and performance. Cooling during exercise has the potential to attenuate detrimental increases in body temperature and improve exercise capacity and performance. Objective The objective of this review was to assess the effectiveness of practical cooling strategies applied during continuous exercise in hot environments on body temperature, heart rate, whole body sweat production, rating of perceived exertion (RPE), thermal perception and exercise performance. Methods Electronic database searches of MEDLINE, SPORTDiscus, Scopus and Physiotherapy Evidence Database (PEDro) were conducted using medical subject headings, indexing terms and keywords. Studies were eligible if participants were defined as ‘healthy’, the exercise task was conducted in an environment ≥25 °C, it used a cooling strategy that would be practical for athletes to use during competition, cooling was applied during a self-paced or fixed-intensity trial, participants exercised continuously, and the study was a randomised controlled trial with the comparator either a thermoneutral equivalent or no cooling. Data for experimental and comparator groups were meta-analysed and expressed as a standardised mean difference and 95 % confidence interval. Results Fourteen studies including 135 participants met the eligibility criteria. Confidence intervals for meta-analysed data included beneficial and detrimental effects for cooling during exercise on core temperature, mean skin temperature, heart rate and sweat production during fixed-intensity exercise. Cooling benefited RPE and thermal perception during fixed-intensity exercise and improved self-paced exercise performance. Conclusion Cooling during fixed-intensity exercise, particularly before a self-paced exercise trial, improves endurance performance in hot environments by benefiting RPE and thermal perception, but does not appear to attenuate increases in body temperature

Patients awaiting surgical repair for large abdominal aortic aneurysms are able to exercise at moderate to hard intensities with a low risk of adverse events

Purpose: Intervention fidelity refers to the extent an experimental manipulation has been implemented as intended. Our aim was to evaluate the fidelity high-intensity interval training (HIT) in patients awaiting repair of large abdominal aortic aneurysms. Methods: Following a baseline cardiopulmonary exercise test, 27 participants performed a hospital-based, supervised HIT intervention in the four weeks preceding surgery. The intervention was performed thrice weekly on a cycle ergometer and involved either 8 × 2-min intervals, each interspersed by 2-min recovery periods, or 4 × 4-min intervals interspersed with 4-min recovery periods. When surgery was delayed, participants undertook one maintenance HIT session per week until surgery. Session one power output was set to baseline anaerobic threshold power output and then increased on subsequent sessions until ratings of perceived exertion (RPE; Borg CR-10) for the legs (RPE-L) and sense of breathlessness/ chest (RPE-C) were hard (5) to very hard (7) at the end of each interval. For safety, power output was maintained or reduced if systolic blood pressure exceeded 180 mm Hg or heart rate exceeded 95% of maximum. Results: Overall session attendance across the 4-week HIT intervention was 74%. Seventeen participants met our compliance criteria of ≥75% of intervention sessions and all maintenance sessions. When compared to non-compliance, compliant participants had higher fitness, performed more HIT sessions and were able to exercise at higher exercise intensities with a lower proportion of exercise safety breaches. In the 17 compliant participants, the proportion of repetitions meeting the HIT criterion was 30% (RPE-L) and 16% (RPE-C). Mean repetition intensity was 4.1 ± 2.0 Arbitrary Units [AU] (RPE-L) and 3.5 ± 1.9 AU (RPE-C) with a within-subject variability of ±1.4 AU and ±1.6 AU, respectively. We observed higher RPE scores (~0.5 AU) following 2-min intervals when compared to 4-min intervals and exercise power output increased 23% across the 4-week HIT intervention. One participant experienced an adverse event but were still able to complete their remaining exercise sessions. Conclusions: Despite an inconsistent and lower than prescribed intensity, it is possible to exercise this high-risk patient population at moderate to hard intensities with a low risk of adverse events

The BASES Expert Statement on Exercise Training for People with Intermittent Claudication due to Peripheral Arterial Disease

Lower-limb peripheral arterial disease (PAD) is a type of cardiovascular disease in which the blood vessels (arteries) that carry blood to the legs and feet are hardened and narrowed or blocked by the build-up of fatty plaques (called atheroma). It affects around 13% of adults over 50 years old, and major risk factors for its development include smoking, diabetes mellitus, and dyslipidaemia (Morley, Sharma, Horsch & Hinchliffe, 2018). The presence of PAD itself is also a risk factor for other cardiovascular problems, such as angina, heart attack and stroke. This is because the underlying disease process, atherosclerosis, is a systemic process, meaning that blood vessels elsewhere in the body may also be affected.The most common symptom of PAD is intermittent claudication (IC), which is muscle pain or discomfort in the legs and/or buttocks brought on by walking and relieved within minutes on rest (Figure 1). It occurs due to an inability to increase blood flow (and oxygen delivery) sufficiently to match the metabolic demands of the lower-limb muscles during exercise. The walking distance or speed at which symptoms occur depends on multiple factors including the severity and site of the arterial disease, walking pace, terrain, incline and footwear. Nevertheless, IC can cause marked reductions in functional capacity and quality of life (Morley et al., 2018).Treatments for IC, aimed at relieving symptoms and reducing the risk of further cardiovascular disease, include lifestyle changes (e.g., stopping smoking, exercising more), vasoactive drugs (e.g. naftidrofuryl oxalate), and revascularisation (i.e. angioplasty or bypass surgery). In 2012, the United Kingdom’s National Institute of Health and Care Excellence (NICE) published a clinical guideline on the management of PAD, which stated that a supervised exercise programme should be offered as a first-line therapy for IC (NICE, 2012). This statement provides an overview of the evidence on exercise training and recommendations for people delivering exercise programmes to this population

Effects of a pragmatic lifestyle intervention for reducing body mass in obese adults with obstructive sleep apnoea: a randomised controlled trial

This study investigated the effects of a pragmatic lifestyle intervention in obese adults with continuous positive airway pressure-treated obstructive sleep apnoea hypopnoea syndrome (OSAHS). Sixty patients were randomised 1 : 1 to either a 12-week lifestyle intervention or an advice-only control group. The intervention involved supervised exercise sessions, dietary advice, and the promotion of lifestyle behaviour change using cognitive-behavioural techniques. Outcomes were assessed at baseline (week 0), intervention end-point (week 13), and follow-up (week 26). The primary outcome was 13-week change in body mass. Secondary outcomes included anthropometry, blood-borne biomarkers, exercise capacity, and health-related quality of life. At end-point, the intervention group exhibited small reductions in body mass (−1.8 [−3.0, −0.5] kg; P = 0.007) and body fat percentage (−1 [−2, 0]%; P = 0.044) and moderate improvements in C-reactive protein (−1.3 [−2.4, −0.2] mg·L−1; P = 0.028) and exercise capacity (95 [50, 139] m; P <0.001 ). At follow-up, changes in body mass (−2.0 [−3.5, −0.5] kg; P = 0.010), body fat percentage (−1 [−2, 0]%; P = 0.033), and C-reactive protein (−1.3 [−2.5, −0.1] mg·L−1; P = 0.037 ) were maintained and exercise capacity was further improved (132 [90, 175] m; P <0.001). This trial is registered with ClinicalTrials.gov NCT01546792

A higher effort-based paradigm in physical activity and exercise for public health: making the case for a greater emphasis on resistance training

It is well known that physical activity and exercise is associated with a lower risk of a range of morbidities and all-cause mortality. Further, it appears that risk reductions are greater when physical activity and/or exercise is performed at a higher intensity of effort. Why this may be the case is perhaps explained by the accumulating evidence linking physical fitness and performance outcomes (e.g. cardiorespiratory fitness, strength, and muscle mass) also to morbidity and mortality risk. Current guidelines about the performance of moderate/vigorous physical activity using aerobic exercise modes focuses upon the accumulation of a minimum volume of physical activity and/or exercise, and have thus far produced disappointing outcomes. As such there has been increased interest in the use of higher effort physical activity and exercise as being potentially more efficacious. Though there is currently debate as to the effectiveness of public health prescription based around higher effort physical activity and exercise, most discussion around this has focused upon modes considered to be traditionally ‘aerobic’ (e.g. running, cycling, rowing, swimming etc.). A mode customarily performed to a relatively high intensity of effort that we believe has been overlooked is resistance training. Current guidelines do include recommendations to engage in ‘muscle strengthening activities’ though there has been very little emphasis upon these modes in either research or public health effort. As such the purpose of this debate article is to discuss the emerging higher effort paradigm in physical activity and exercise for public health and to make a case for why there should be a greater emphasis placed upon resistance training as a mode in this paradigm shift

Effect of hand cooling on body temperature, cardiovascular and perceptual responses during recumbent cycling in a hot environment

Exercise in hot environments increases body temperature and challenges the function of cardiovascular, metabolic and thermoregulatory systems. Elevated body temperature as a consequence of prolonged and/or intense exercise impairs athletic performance and increases the risk of heat illness and serious medical conditions. Pre-exercise cooling techniques have been used to lower body temperature and increase heat storage capacity during exercise. Head, neck and wrist cooling have also been employed to reduce physiological strain in hot environments. Although the majority of these methods have proven useful, some are impractical for use during exercise when heat strain is most pronounced. Hand cooling during exercise has the potential to alleviate these impracticalities and attenuate increases in body temperature due to the hands large surface to mass ratio, low metabolic heat production, large blood supply and rapid cooling rates. Reductions in body temperature after bouts of exercise and improvements in exercise performance have been observed using various hand cooling protocols. However, the effectiveness of hand cooling during exercise in a hot environment and the mechanisms of action are unclear. The purpose of the study was to quantify physiological and perceptual responses to hand immersion in water during recumbent cycling in a hot environment. In a randomised control design 7 well-trained males (body mass 79.8 s 6.3 kg; stature 182 s 5 cm; age 23 s 3 years; recumbent cycling V ̇O2peak 41 s 5 ml•kg-1•min-1) who were naïve to the study aims provided informed consent to participate in 3 trials. Participants immersed their hands in 8, 14 and 34°C water whilst cycling at an intensity (W) equivalent to 50% V ̇O2peak for 60 min in an environmental chamber maintained at 35°C 50% relative humidity. Intestinal and 4-site mean skin temperature and heart rate were monitored continuously and mean-averaged over 5 minute intervals. Rating of perceived exertion and thermal strain were assessed every 5 minutes. Data was assessed for normality and homogeneity of variance. The likelihood (% chance) of between group differences was assessed using a magnitude-based approach, Cohen's standardised difference score (d = 0.20 small, 0.5 moderate and 0.8 large effect) and 90% confidence intervals for [d]. Change in intestinal temperature was likely (84%) less in 8°C; 0.43 s 0.16°C versus 34°C; 0.55 s 0.16°C after 15 min; d = 0.73 [-0.19 to 1.65] and very likely (98%) less in 8°C; 0.78 s 0.28°C versus 34°C; 1.22 s 0.16°C after 40 min d = 1.36 [0.47 to 2.25]. Change in mean skin temperature was likely (87%) less in 8°C; -0.05 s 0.39°C versus 34°C; 0.31 s 0.46°C; d = 0.81 [0.09 to 1.71] after 5 min, very likely (98%) less after 15 min; -0.09 s 0.72°C versus 0.77 s 0.30°C; d = 1.24 [0.45 to 2.03] and onwards to cessation of exercise. Percentage of peak heart rate was likely (94%) lower in 8°C; 87 s 4% versus 34°C; 90 s 5% from 25 min onwards; d = 0.69 [0.18 to 1.20]. After 5 min of exercise rating of perceived exertion was likely (77%) lower in 8°C; 12.6 s 1.0 versus 34°C 13.4 s 1.7; d = 0.61 [-0.36 to 1.57] but was likely similar from 25 min onwards. Perception of thermal strain was likely (92%) lower in 8°C; 6.5 s 0.5 versus 34°C; 7.2 s 0.4 after 5 min exercise; d = 0.81 [0.09 to 1.71] and was almost certainly (>99%) lower; 7.3 s 0.7 versus 8.0 s 0.7 for the remainder of the trial; d = 1.21 [0.65 to 1.77]. Similar beneficial effects were observed for 14°C versus 34°C immersion but the magnitude of the effects was smaller than 8°C immersion. Small-to-moderate differences were observed between 8°C and 14°C immersion. The findings suggest that hand cooling during fixed moderate-intensity cycling in a hot environment has the potential to alleviate increases in body temperature, cardiovascular demand and perceptions of exertion and thermal strain. Greatest effects were observed when the hands were immersed in 8°C water compared with 14°C. Augmented heat loss at the palm-water surface might enable cooler blood to return to core and shell regions; increasing the thermal gradient between active tissue and blood thus improving internal heat transfer, maintaining a wide core to skin temperature gradient and reducing heat storage. Limiting the increase in body temperature might have lowered cardiovascular demands by reducing the requirement for cutaneous vasodilation thus lowering physiological strain. These combined effects are manifested in lowered perceptions of exertion and thermal strain. The findings from this study suggest that endurance exercise in hot environments might be improved by hand cooling and future research should investigate its effectiveness during cycling and running performance