The impact of short duration, high intensity exercise on cardiac troponin release

The aim of this study was to assess the appearance of cardiac troponins (cTnI and/or cTnT) after a short bout (30 s) of ‘all-out’ intense exercise and to determine the stability of any exercise-related cTnI release in response to repeated bouts of high intensity exercise separated by 7 days recovery. Eighteen apparently healthy, physically active, male university students completed two all-out 30 s cycle sprint, separated by 7 days. cTnI, blood lactate and catecholamine concentrations were measured before, immediately after and 24 h after each bout. Cycle performance, heart rate and blood pressure responses to exercise were also recorded. Cycle performance was modestly elevated in the second trial [6·5% increase in peak power output (PPO)]; there was no difference in the cardiovascular, lactate or catecholamine response to the two cycle trials. cTnI was not significantly elevated from baseline through recovery (Trial 1: 0·06 ± 0·04 ng ml−1, 0·05 ± 0·04 ng ml−1, 0·03 ± 0·02 ng ml−1; Trial 2: 0·02 ± 0·04 ng ml−1, 0·04 ± 0·03 ng ml−1, 0·05 ± 0·06 ng ml−1) in either trial. Very small within subject changes were not significantly correlated between the two trials (r = 0·06; P>0·05). Subsequently, short duration, high intensity exercise does not elicit a clinically relevant response in cTnI and any small alterations likely reflect the underlying biological variability of cTnI measurement within the participants.

Role of active and passive recovery in adaptations to high intensity training

It has been established that Wingate-based high-intensity training (HIT) consisting of 4 to 6 x 30-s all-out sprints interspersed with 4-min recovery is an effective training paradigm. Despite the increased utilisation of Wingate-based HIT to bring about training adaptations, the majority of previous studies have been conducted over a relatively short timeframe (2 to 6 weeks). However, activity during recovery period, intervention duration or sprint length have been overlooked. In study 1, the dose response of recovery intensity on performance during typical Wingate-based HIT (4 x 30-s cycle all-out sprints separated by 4-min recovery) was examined and active recovery (cycling at 20 to 40% of V̇O2peak) has been shown to improve sprint performance with successive sprints by 6 to 12% compared to passive recovery (remained still), while increasing aerobic contribution to sprint performance by ~15%. In the following study, 5 to 7% greater endurance performance adaptations were achieved with active recovery (40%V̇O2peak) following 2 weeks of Wingate-based HIT. In the final study, shorter sprint protocol (4 to 6 x 15-s sprints interspersed with 2 min of recovery) has been shown to be as effective as typical 30-s Wingate-based HIT in improving cardiorespiratory function and endurance performance over 9 weeks with the improvements in V̇O2peak being completed within 3 weeks, whereas exercise capacity (time to exhaustion) being increased throughout 9 weeks. In conclusion, the studies demonstrate that active recovery at 40% V̇O2peak significantly enhances endurance adaptations to HIT. Further, the duration of the sprint does not seem to be a driving factor in the magnitude of change with 15 sec sprints providing similar adaptations to 30 sec sprints. Taken together, this suggests that the arrangement of recovery mode should be considered to ensure maximal adaptation to HIT, and the practicality of the training would be enhanced via the reduction in sprint duration without diminishing overall training adaptations.

Herbal supplements: Recent findings in exercise, health and weight loss

Natural herbs have been in use for weight loss purposes since history began. However, the current global obesity epidemic and the rise in obesity-related chronic diseases, including type-II diabetes and cancer, have highlighted the need for novel and effective approaches for herbal remedies. Whilst the popularity of several prescribed and non-prescribed slimming aids and herbal plant supplements have been marketed for their weight loss efficacy, single and multi-ingredient herbal supplements are still being investigated for their single or combined weight loss benefits. Limited research have highlighted an interesting efficacy for several popular herbal plant supplements including caffeine and capsaicin, Ayurvedic preparations and herbal teas, resulting in various degrees of effectiveness including thermogenic, appetite control and psychological benefits such as mood state. Recent research has suggested acute augmented weight-loss effects of combining herbal ingestion with exercise. For example, ingesting green tea, yerba mate and/or caffeine have been shown to increase metabolic rate, and augmented fatty acid metabolism and to increase energy expenditure from fatty acid sources during exercise with various intensities, particularly at low and moderate intensities. Other promising weight-loss effects have also been also reported for combining exercise with multi-ingredient herbal supplements, particularly those that are rich in phytochemicals and caffeoyl derivatives. Combining herbal ingestions with exercise still require further research in order to establish the supplementation most effective protocols in terms of dosage and timing, and to determine the long-term benefits, particularly those related to exercise protocols, and the long term adherence to sustain the weight loss outcomes.

The effects of ageing and exercise on skeletal muscle structure and function

Musculoskeletal ageing is associated with profound morphological and functional changes that increase fall risk and disease incidence and is characterised by age-related reductions in motor unit number and atrophy of muscle fibres, particularly type II fibres. Decrements in functional strength and power are relatively modest until the 6th decade, after which the rate of loss exponentially accelerates, particularly beyond the 8th decade of life. Physical activity is a therapeutic modality that can significantly attenuate age-related decline. The underlying signature of ageing, as manifested by perturbed redox homeostasis, leads to a blunting of acute and chronic redox regulated exercise adaptations. Impaired redox regulated exercise adaptations are mechanistically related to altered exercise-induced reactive oxygen and nitrogen species generation and a resultant failure to properly activate redox regulated signaling cascades. Despite the aforementioned specific impairment in redox signaling, exercise induces a plethora of beneficial effects, irrespective of age. There is, therefore, strong evidence for promoting regular physical exercise, especially progressive resistance training as a lifelong habitual practice.

Sedentariness and physical inactivity in diabetes: a case for home-based exercise prescription

Increasing proportions of the global population are being diagnosed with diabetes. It is anticipated that by 2030, 10% of the adult population worldwide will be living with this condition. Lifestyle factors can impact on the development, management and progression of diabetes. Obesity and sedentary living are contributory factors to the increased volume of diabetes. Physical activity offers those living with diabetes the opportunities to keep well and attain potentially more stable blood glucose control reducing the level of medical intervention required and delaying or preventing some of the life-changing complications that can derive from a diabetes diagnosis. Exercise interventions are effective in preventing and treating type-II diabetes. However, maintaining regular exercise routines, especially home-based exercises may provide a key for sustaining the health benefits.

Workplace sedentary health risks and exercise interventions

Sedentary lifestyle and physical inactivity are causes of major health risks including cardiovascular disease (CVD), diabetes and cancer. Workplace is an ideal setting to understand both the prevalence of these risks and for devising and implementing effective intervention strategies. It is now possible to perform direct workplace assessments to identify the sedentary prevalence and assess the sedentary related health risks, which can include assessing the risks of atherosclerosis, hypertension, hypercholesterolemia, hyperglyaemia and reduced cardiorespiratory capacity. Based on evaluating the workplace health risks, it is possible to identify individuals who may be at higher CVD risk so they can be targeted with a risk-reduction intervention that can also be tailored towards improving healthy behaviours, especially towards physical activity activity and exercise. This chapter explains workplace sedentary risks, and provides examples of CVD risk prevalence, particularly within the university campus workplace, and presents examples of an exercise based targeted interventions aimed at reducing CVD risks amongst high risk sedentary employees.

Characteristics of preferred gait patterns: considerations for exercise prescription

Gait patterns have been widely studied in different fields of science for their particular characteristics. A dynamic approach of human locomotion considers walking and running as two stable behaviors adopted spontaneously under certain levels and natures of constraints. When no constraints are imposed, people naturally prefer to walk at the typical speed (i.e., around 4.5 km.h-1) that minimizes metabolic energy cost. The preferred walking speed (PWS) is also known to be an indicator of mobility and an important clinical factor in tracking impairements in motor behaviors. When constrained to move at higher speeds (e.g., being late), people naturally switch their preference to running for similar optimization reasons (e.g., physiological, biomechanical, perceptual, attentionnal costs). Indeed, the preferred transition speed (PTS) marks the natural seperation between walking and running and consistently falls within a speed range around 7.5 km.h-1. This chapter describes the constraint-dependant spontaneous organisation of the locomotor system, specifically on the walk-to-run speed continuum. We provide examples of the possibility of long-term adaptations of preferred behaviors to specific constraints such as factors related to traditional clothing or practice. We use knowledge from studies on preferred behaviors and on the relationship between affect and exercise adherence as a backdrop to prescribing a walk exercise program with an emphasis on populations with overweight or obesity.