Exercise duration: Independent effects on acute physiologic responses and the need for an individualized prescription.

An individualization of exercise prescription is implemented mainly in terms of intensity but not for duration. To survey the need for an individualized exercise duration prescription, we investigated acute physiologic responses during constant-load exercise of maximal duration (tmax ) and determined so-called duration thresholds. Differences between absolute (min) and relative terms (% tmax ) of exercise duration were analyzed. Healthy young and trained male and female participants (n = 11) performed an incremental exercise test and one tmax constant-load exercise test at a target intensity of 10% of maximal power output below the second lactate turn point (LTP2 ). Blood lactate, heart rate, and spirometric data were measured during all tests. tmax was markedly different across subjects (69.6 ± 14.8 min; range: 40-90 min). However, distinct duration phases separated by duration thresholds (DTh) were found in most measured variables. These duration thresholds (except DTh1) were significantly related to tmax (DTh2: r2  = 0.90, p < 0.0001; DTh3: r2  = 0.98, p < 0.0001) and showed substantial interindividual differences if expressed in absolute terms (DTh2: 24.8 ± 6.0 min; DTh3: 47.4 ± 10.6 min) but not in relative terms (DTh2: 35.4 ± 2.7% tmax ; DTh3: 67.9 ± 2.4% tmax ). Our data showed that (1) maximal duration was individually different despite the same relative intensity, (2) duration thresholds that were related to tmax could be determined in most measured variables, and (3) duration thresholds were comparable between subjects if expressed in relative terms. We therefore conclude that duration needs to be concerned as an independent variable of exercise prescription.

Sex-based differences in sub-technique selection during an international classical cross-country skiing competition.

The purpose of this study was to compare speed, sub-technique selection and temporal patterns between world-class male and female cross-country (XC) skiers and to examine the combined associations of sex and speed on sub-technique selection. Thirty-three XC skiers performed an international 10-km (women; n = 8) and 15-km (men; n = 25) time-trial competition in the classical style (with the first 10 km of the race being used for analyses). An integrated GNSS/IMU system was used to continuously track position speed and automatically classify sub-techniques and temporal patterns (i.e. cycle length and-rate). When comparing the eight highest ranked men and women, men spent less time than women (29±2 vs. 45±5% of total time) using diagonal stride (DIA), more time (44±4 vs. 31±4%) using double poling (DP) and more time (23±2 vs. 19±3%) using tucking and turning (all P < .01). Here, men and women used these sub-techniques at similar temporal patterns within the same speed-intervals; although men employed all sub-techniques at steeper uphill gradients (all P < .05). In subsequent analyses including all 33 skiers, adjustment for average racing speed did not fully attenuate the observed sex differences in the proportion of time using DIA (CI95% [-10.7, -1.6]) and DP (CI95% [0.8, 9.3]). Male world-class XC skiers utilized less DIA and more DP compared to women of equal performance levels. Although these differences coincided with men's higher speed and their ability to use the various sub-techniques at steeper uphill gradients, sexual dimorphism in the proportional use of DIA and DP also occurred independently of these speed-differences.

Assessment of Walking Routes as a Possible Approach for Promoting Physical Activity in Children with Autism Spectrum Disorder: Brief Report.

Children with autism spectrum disorder (ASD) are at increased risk for being overweight/obese and face a variety of challenges with achieving the recommended levels of physical activity. Physical activity level has additionally been linked to motor skills, sleep, cognitive function and academic performance, and mental health in children with ASD. We pilot tested the feasibility and preliminary efficacy of walking routes as a novel approach to increasing physical activity among children with ASD. Physical activity was measured by accelerometry in 21 children ages 6-10 years. Participants received feedback on their physical activity and were counseled on using their surrounding neighborhoods to increase their physical activity. Non-completion (n = 9) reasons included equipment discomfort, family challenges, and diagnosis misattribution. While small changes in physical activity level and sedentary time were observed, neither was statistically significant. Further controlled studies on walking route interventions should continue to explore the potential benefits among this high-risk population.

Epidemiology of injuries among amateur athletes who attended fitness activities: the role of the qualification of the trainer.

BACKGROUND: The fitness trainer could have an important role in the prevention of injuries among fitness attendants. In several Countries, including Italy, there is not a formal regulation about the qualification of fitness trainers. The aim of our study is to estimate the incidence of injuries in a sample of amateur fitness athletes training in Apulia (southern Italy) and evaluate if being the presence of a trainer graduated in Sports and Movement Science could be a protective factor for injuries. METHODS: This is a retrospective, cross-sectional study, carried out in a convenience sample of amateur athletes enrolled in 16 Apulian fitness centers. The survey was carried out by an anonymous self-administered questionnaire distributed and compiled in the gym. RESULTS: We enrolled 205 amateur athletes, of which 105/205 (51.2%) cared by a trainer graduated in Sports and Movement Science and 100/205 (48.8%) trained by a person with a qualification from Olympic Committee or Sport Federation. The incidence rate of injury ×1000 person-months of training is 6.1 (95%CI=4.4-8.1), 5.5 (95%CI=3.1-9.2) among athletes trained by graduated and 6.3 (95%CI=4.2-9.2) in ones trained by a person with a different qualification (IRR=1.1; 95%CI=0.6-2.3; P=0.348). CONCLUSIONS: Our study showed a mild lifetime prevalence of injury among subjects attending fitness activities (21%), higher among athletes trained by an instructor not graduated in Sports Science. This is a topic poorly investigated previously but very important in the future, in particular in the view of the diffusion of fitness worldwide.

Oxygen uptake plateau: calculation artifact or physiological reality?

PURPOSE: To test whether the oxygen uptake ([Formula: see text]) plateau at [Formula: see text] is simply a calculation artifact caused by the variability of [Formula: see text] or a clearly identifiable physiological event. METHODS: Forty-six male participants performed an incremental ramp and a [Formula: see text] verification test. Variability of the difference between adjacent sampling intervals (difference) and of the slope of the [Formula: see text]-workload relationship (slope) in the submaximal intensity domain were calculated. Workload defined sampling intervals used for the calculation of the difference and slope were systematically increased from 20 to 100 W until the expected risk of false plateau diagnoses based on the Gaussian distribution function was lower than 5%. Overall, more than 1500 differences and slopes were analyzed. Subsequently, frequencies of plateau diagnoses in the submaximal and maximal intensity domains were compared. RESULTS: Variability of the difference and slope decreased with increasing sampling interval (p < 0.001). At a sampling interval of 50 W, the predefined acceptable risk of false plateau diagnoses (≤ 5%) was achieved. At this sampling interval, the actual frequency (1.4%) of false-positive plateau diagnoses did not differ from the expected frequency in the submaximal intensity domain (1.6%; p = 0.491). In contrast, the actual frequency at maximal intensity (35.7%) was significantly higher compared to the submaximal intensity domain (p < 0.001) and even higher than the expected frequency of false-positive diagnoses (p < 0.001). CONCLUSION: The [Formula: see text] plateau at [Formula: see text] represents a physiological event and no calculation artifact caused by [Formula: see text] variability. However, detecting a [Formula: see text] plateau with sufficient certainty requires large sampling intervals.

No acute effects of placebo or open-label placebo treatments on strength, voluntary activation, and neuromuscular fatigue.

PURPOSE: Recent evidence suggests that deception may not be necessary for placebos to improve clinical outcomes. We tested the hypothesis that placebo and open-label placebo (OLP) treatments would acutely improve strength and voluntary activation, as well as minimize neuromuscular fatigue, in untrained participants. METHODS: Twenty-one males (n = 11) and females (n = 10) visited the laboratory on three occasions (placebo, OLP, control) to receive each treatment in a randomized, counter-balanced manner. Trials involved a pretest, a 15-min intervention, and posttests. For the placebo trial, participants were informed that they would be ingesting a capsule that would improve their performance and make them feel more energetic. For the OLP intervention, participants were told that the capsules would have no effects. In "Experiment #1", knee extensor maximal voluntary contraction (MVC) peak torque and percent voluntary activation were evaluated. In "Experiment #2", participants performed 20 consecutive MVCs while surface electromyographic signals were detected from the vastus lateralis. Subjective assessments of energy and perceived exertion were examined. RESULTS: The interventions had no effect on strength or voluntary activation, but energy levels increased following treatments (p = 0.016, η2 = 0.257). Neither treatment influenced neuromuscular fatigue. Though some variables showed moderate-to-large effect sizes, these results were consistent for individuals with lower voluntary activation. CONCLUSION: Placebo and OLP treatments had minimal influence on strength, voluntary activation, and fatigue resistance. As these findings differ from recent reports, we speculate that placebos and OLPs are more likely to enhance muscle function in patient populations seeking medical care.

Quantification of aerobic determinants of performance in post-pubertal adolescent middle-distance runners.

PURPOSE: The use of oxygen cost ([Formula: see text]aero) parameters to predict endurance performance has recently been criticized. Instead, it is suggested that aerobic energy cost ([Formula: see text]) provides greater validity; however, a comparison of these quantification methods has not previously been made. METHODS: Fifty-six male (n = 34) and female (n = 22) competitive adolescent (17 ± 1 years) middle-distance runners participated in a sub-maximal and maximal incremental treadmill test. Running economy (RE) was measured at the speed corresponding to lactate turnpoint, and the three speeds prior. Maximal oxygen uptake ([Formula: see text]O2max), speed at [Formula: see text]O2max and fraction of [Formula: see text]O2max utilized across a range of intensities, and speeds from 0.8, 1.5 and 3 km races were also quantified. RE and fractional utilization were calculated in units of [Formula: see text]aero and [Formula: see text]aero. RESULTS: Multiple linear regression models demonstrated no discernible difference in the predictive capability of RE, fractional utilization and [Formula: see text]O2max when expressed as [Formula: see text]aero or [Formula: see text]aero in both sexes. When plotted as a function of running speed, [Formula: see text]aero displayed a stepwise decrease (F = 11.59, p < 0.001) whereas [Formula: see text]aero exhibited a curvilinear response (F = 4.74, p = 0.015). Differences were also evident in the slopes plotted for %[Formula: see text]O2max and %[Formula: see text]aeromax against running speed (F = 5.38, p = 0.021). CONCLUSIONS: Quantifying aerobic determinants of performance in units of [Formula: see text]aero provides no greater validity compared to [Formula: see text]aero-based measurement. Although both [Formula: see text]aero and [Formula: see text]aero are sensitive to changes in speed, [Formula: see text]aero provides the more valid reflection of the underlying metabolic cost of running. Physiologists should also be aware of the potential differences between expression of aerobic running intensity based upon %[Formula: see text]O2max compared to %[Formula: see text]aeromax.

Effect of yoga on vigilance, self rated sleep and state anxiety in Border Security Force personnel in India.

BACKGROUND: Military occupations require heightened vigilance with resultant sleep disturbances, increased anxiety and reduced vigilance. OBJECTIVE: To compare yoga with physical training to reduce insomnia, anxiety and increase vigilance in security personnel. METHODS: One hundred and twelve Border Security Force personnel (BSF group, males; mean age±SD = 30.4±7.4 years) were compared with 112 personnel of a private security firm (SIS group). The BSF group received yoga for nine days and the SIS group received physical training for the same period. Assessments were at baseline and after 9 days, with the digit vigilance test (DVT), Spielberger's STAI-S, and a sleep rating questionnaire. RESULTS: (1) Between groups: (i) at baseline the BSF group had higher vigilance and more daytime naps compared to the SIS group and (ii) after nine days the SIS group had higher state anxiety compared to the BSF group (ANOVA, Bonferroni adjusted post-hoc comparisons; SPSS Version 24.0) (2) In post-pre intervention comparisons (i) the BSF group increased vigilance and decreased state anxiety after yoga, with improved sleep, while (ii) the SIS group showed increased vigilance after physical training. CONCLUSION: Yoga may improve sleep, reduce anxiety while increasing vigilance in occupations requiring vigilance.

Medical Encounters During the United States Army Special Forces Assessment and Selection Course.

INTRODUCTION: The Special Forces Assessment and Selection (SFAS) is an extremely physically and mentally demanding 19- to 20-day course designed to determine whether Soldiers are qualified to enter the Special Forces Qualification Course. As a first step to understand medical problems during SFAS, this study examined injuries, illnesses, and activities associated with injuries during the course. MATERIALS AND METHODS: Medical events during the SFAS course were compiled from Sick Call Trackers (a log of medical encounters maintained by medical personnel in the field) and Chronology of Medical Care (Standard Form 600). Descriptive statistics were calculated for each injury and illness and injuries were compiled by the activities performed when the injuries occurred. RESULTS: Of the 800 Soldiers who volunteered for the study, 38% (n = 307/800) and 12% (n = 97/800) experienced one or more injuries and/or illnesses, respectively. The most common injuries were blisters and abrasions/lacerations with incidences of 20% (n = 158/800) and 13% (104/800), respectively. The most common illnesses were respiratory infections, other infections, contact dermatitis, and allergies with incidences of 7% (n = 57/800), 2% (n = 14/800), 2% (n = 14/800), and 2% (n = 13/800), respectively. Among all injuries recorded (n = 573), the most common were blisters (46%), abrasions/lacerations (24%), pain (not otherwise specified) (19%), tendonitis (3%), and sprains (3%). Among all illnesses recorded (n = 133), the most common were respiratory infections (56%), allergies (11%), contact dermatitis (11%), and other infections (11%). Most injuries were experienced during land navigation (44%), team events (20%), and foot marching (11%), running (6%), and the obstacle course (5%), but when the estimated time involved for each event was considered, activities with the highest injury rates were the obstacle course (65 injuries/hr), running (27 injuries/hr), the Combat Readiness Assessment (activity involving combat-related tasks) (20 injuries/hr), and foot marching (16 injuries/hr). CONCLUSION: The major limitations of this investigation were: 1) the low specificity with regard to many of the diagnoses/complaints; and 2) the fact that the medical problems reported here are only those seen by medical care providers and are likely an underestimate of the total morbidity in the SFAS course. Soldiers often self-treat and some may be reluctant to see medical personnel because of how it might affect their rating in the course. Nonetheless, this investigation alerts medical personnel to the injuries and illnesses to expect, and public health workers and leadership with activities to target for injury prevention measures during SFAS.

Impact of exercise training on cardiovascular disease and risk.

Epidemiological studies in large cohorts support the notion that physical fitness is associated with reduced cardiovascular mortality and hospitalization due to cardiovascular disease. During the last 20 years even the concept of resting inactive after a myocardial infarction has dramatically changed and nowadays patients are mobilized and included into exercise training programs very shortly after the insult. Unfortunately, these beneficial effects of exercise training are independent of the genetic background and are only observed in case the training program is not paused for a longer time. Therefore, to take advantage of the effects of exercise training in health care the challenge for the future is to increase exercise compliance by offering interesting and effective exercise training programs. At the physiological and molecular level, exercise training affects several organs like the vascular system and the skeletal muscle. Changes elicited by regular exercise training range in the vascular system from increasing vasodilation due to an elevation of bioavailable nitric oxide to a shift in the catabolic/anabolic balance in the peripheral skeletal muscle. In this review we discuss the healthy benefit of exercise training and the molecular changes triggered by exercise training in the setting of secondary prevention.

Does exercise intensity increment in exergame promote changes in strength, functional capacity and perceptual parameters in pre-frail older women? A randomized controlled trial.

The aim of this study was to compare the effects of two exercise intensities on exergame training program in muscle strength, functional capacity and perceptual parameters in pre-frail older women. Thirty-four women (69.5 ±â€¯5.4 years) were randomly assigned to either moderate- (MG: 11-13 perceived exertion) or vigorous-exercise intensity group (VG: 14-16 perceived exertion). Muscle strength and functional capacity were evaluated before and after 3 months of training. The affective responses were measured once a week and perceived benefit was evaluated after training period. The MG improved the average power at 60°/s from pre- to post-training (p < 0.002) on the knee extensor (pre = 100.0 ±â€¯15.9 W; post = 115.2 ±â€¯22.6 W), flexor (pre = 22.3 ±â€¯6.1 W; post = 29.1 ±â€¯7.9 W) and plantiflexor muscles (pre = 11.4 ±â€¯5.9 W; post = 21.2 ±â€¯4.2 W). MG presented greater average power at post-training than VG for knee extensor (20%) and flexor muscles (23%) (p < 0.039). There was main time effect of peak torque at 180°/s for knee extensor (pre = 74.15 ±â€¯14.28 N·m/kg; post = 81.31 ±â€¯18.4 N·m/kg), flexor (pre = 43.01 ±â€¯12.43 N·m/kg; post = 48.3 ±â€¯9.11 N·m/kg) and plantiflexor muscles (pre = 29.2 ±â€¯13.76 N·m/kg; post = 36.87 ±â€¯9.7 N·m/kg) as well as average power (pre = 41.15 ±â€¯15.67 W; post = 48.42 ±â€¯11.8 W) and work (pre = 99.92 ±â€¯38.53 J; post = 117.03 ±â€¯25.56 J) on the knee flexor muscles (p < 0.046). MG improved timed up and go performance from pre- to post-training (pre = 10.0 ±â€¯0.32 s; post = 8.1 ±â€¯1.6 s, p = 0.001), whereas both groups improved 10 m-walk performance (pre = 1.33 ±â€¯0.25 s, post = 1.5 ±â€¯0.24 s; p = 0.003). Positive affect (2.64 ±â€¯0.02) and pleasure (15.8 ±â€¯0.6) for MG were greater than VG at post-training (2.36 ±â€¯0.03; p < 0.001; 14.4 ±â€¯0.5; p < 0.03). Therefore, regardless of the exercise intensity, exergame training improved muscle strength and functional capacity in pre-frail older women. However, positive affect and pleasure were reported only when older women practiced exergame with moderate exercise intensity.

Moving beyond threshold-based dichotomous classification to improve the accuracy in classifying non-responders.

We examined maximal oxygen consumption responses following exercise training to demonstrate the limitations associated with threshold-based dichotomous classification of responders and non-responders and proposed alternative methods for classification. Specifically, we: 1) calculated individual probabilities of response, and 2) classified individuals using response confidence intervals (CI) and reference points of zero and a smallest worthwhile change of 0.5 METs. Our findings support the use of individual probabilities and individual CIs to improve the accuracy in non-response classification.

Can grip strength be used as a surrogate marker to monitor recovery from shoulder fatigue?

Muscular fatigue impacts on normal shoulder function, which is particularly pertinent to throwing athletes. This study aimed to investigate the relationship between grip strength and shoulder muscle fatigue to evaluate the role of grip strength as a surrogate measure for upper limb performance. Twenty healthy participants were recruited. EMG was recorded from 15 shoulder muscles during different fatiguing contractions: an initial baseline recording (Fat-Baseline); after a shoulder exhausting exercise regime (Fat-Exhaustion); and after a 10 min rest period (Fat-Recovery). Grip strength was similarly measured in the same conditions. Grip strength differed significantly across the testing scenarios (p = 0.012-<0.001). Greater fatigue was seen in anterior deltoid, middle deltoid, posterior deltoid and supraspinatus in the Fat-Exhaustion contraction as compared to the Fat-Baseline contraction (p = <0.001-0.043). Greater fatigue was seen during the Fat-Recovery contraction for the trapezius, serratus anterior and biceps brachii as compared to the Fat-Exhaustion contraction (p = 0.008-0.038). Grip strength decreased following an exhausting exercise protocol but recovered to baseline following a rest period. Conversely, EMG indices of fatigue did not recover. Additional fatigue was seen reflecting a reorganisation of movement strategy. Therefore, susceptibility to injury still exists if grip strength alone is used as a barometer of upper limb performance.

Pulmonary hypertension and exercise training: a synopsis on the more recent evidences.

The benefits of exercise training in virtually all humans, including those with a clinically stable chronic disease are numerous. The potential value lies in the fact that functional capacity is oftentimes significantly compromised. Exercise training not only play a role in reversing some of the pathophysiologic processes associated with chronic diseases but also improves clinical trajectory. Given the significant pathologic consequences associated with pulmonary hypertension and its implications for deteriorating right ventricular function as well as the perceived potential for a precipitous and possibly critical drop in cardiac output during periods of physical exertion, exercise training was historically not recommended for these patients. More recently, a promising body of literature demonstrating the safety and efficacy of exercise training (with benefit on exercise capacity, peak oxygen consumption and quality of life) in pulmonary hypertension patients has emerged, but the conclusion about the effects of exercise training were non-exhaustive and therefore there is still a lack of knowledge regarding exercise training for these patients. Thus, we aim to ascertain the current effectiveness of exercise rehabilitation for pulmonary hypertension by performing a brief overview on the latest currently available evidences in such an "at a glance" synopsis addressed to summarize/quantify the more recent existing body of literature. KEY MESSAGES Exercise training was historically not recommended in pulmonary hypertension. Recently, exercise training safety-efficacy in pulmonary hypertension has emerged. Exercise training should be recommended in addition to optimal medical therapy.

[Background and Methodology of the Development of German Physical Activity Guidelines]. / Hintergrund und methodisches Vorgehen bei der Entwicklung von nationalen Empfehlungen für Bewegung.

This paper describes the process used to develop the physical activity guidelines for German children and adolescents (0-17 years), adults (18-64 years), older adults ≥65 years and adults with chronic diseases. The German physical activity guidelines were developed by an interdisciplinary working group based on existing guidelines using a 3-phased process. Phase 1: Systematic literature searches for current physical activity guidelines; expert consultation-based development of quality criteria. Phase 2: Evaluation of physical activity guidelines based on the quality criteria; identification and content analysis of high-quality guidelines. Phase 3: Synthesis of content analysis and deduction of German physical activity guidelines. Expert consultation generated 28 quality criteria classified into the 4 domains "A: scope and purpose" (3 items), "B: rigour of development" (10 items), "C: clarity and comprehensiveness of content" (12 items), "D: arrangement and presentation" (3 Items). We identified 66 guidelines scoring ≥60% of the possible rating points in domain A and B as high-quality "source-guidelines" (children and adolescents n=4, adults=16, older adults n=9, 7 chronic diseases n=37). Source-guidelines constitute the database for the development of the German physical activity guidelines. The national physical activity guidelines for children and adolescents, adults, older adults and persons with chronic diseases serve as an evidence-based and quality-controlled basis for physical activity promotion in Germany.

[German National Physical Activity Recommendations for Adults and Older Adults: Methods, Database and Rationale]. / Nationale Bewegungsempfehlungen für Erwachsene und ältere Erwachsene ­ Methodisches Vorgehen, Datenbasis und Begründung.

National physical activity recommendations are regarded as crucial elements of comprehensive physical activity promotion strategies. To date, Germany has no such national physical activity recommendations. The aim of this study was to provide physical activity recommendations based on a comprehensive summary of scientific evidence on the relationships between physical activity and a range of health outcomes in adults and older adults. The recommendations were developed in a 3-phase process (systematic literature review, development and use of quality criteria, synthesis of content) based on already existing high-quality guidelines. Based on the analysis of documents included in this study, the following recommendations were formulated. To gain wide-ranging health benefits, adults and older adults should be physically active regularly and avoid inactivity. Adults and older adults should carry out at least 150 min/week moderate intensity or 75 min/week high intensity aerobic activity. Adults and older adults can also reach the recommended amount of physical activity by performing activities in an appropriate combination in both intensity ranges. Optimally, physical activity should be distributed over the week and it can be accumulated in bouts of at least 10 min. Physical activity beyond 150 min/week yields further health benefits. At the same time, physical activity below 150 min/week is associated with meaningful health gains. Accordingly, all adults and older adults should be encouraged to be physically active whenever possible. Adults and older adults should also perform muscle strengthening activities at least twice a week. Regular balance exercises (3 times a week) can reduce the risk of falls in older adults. Adults and older adults should avoid long periods of sitting and should break up sitting time by physical activity. Physical activity can lead to adverse events, such as musculoskeletal injuries, which can be mitigated through appropriate measures. All in all, the benefits of regular physical activity overweigh by far the risks in both adults and older adults.

[Recommendations for Physical Activity and Sedentary Behaviour for Children and Adolescents: Methods, Database and Rationale]. / Empfehlungen für körperliche Aktivität und Inaktivität von Kindern und Jugendlichen ­ Methodisches Vorgehen, Datenbasis und Begründung.

The benefits of physical activity and a reduction of sedentary behaviour in childhood and adolescence are well established.Based on a quality-assured literature review, the German recommendations were updated. Guidelines for infants, toddlers, children of kindergarten and primary school age and youth are clearly depictedIn general, a higher amount of physical activity is associated with more health benefits. Preschool age children should have 180 min of physical activity daily, and from primary school age on, at least 90 min daily are recommended. Sedentary behaviour, especially time in front of screens, is to be reduced to a minimum.