Article

Aerobic High-Intensity Intervals Improve V˙O2max More Than Moderate Training

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Abstract

The present study compared the effects of aerobic endurance training at different intensities and with different methods matched for total work and frequency. Responses in maximal oxygen uptake (VO2max), stroke volume of the heart (SV), blood volume, lactate threshold (LT), and running economy (CR) were examined. Forty healthy, nonsmoking, moderately trained male subjects were randomly assigned to one of four groups:1) long slow distance (70% maximal heart rate; HRmax); 2)lactate threshold (85% HRmax); 3) 15/15 interval running (15 s of running at 90-95% HRmax followed by 15 s of active resting at 70% HRmax); and 4) 4 x 4 min of interval running (4 min of running at 90-95% HRmax followed by 3 min of active resting at 70%HRmax). All four training protocols resulted in similar total oxygen consumption and were performed 3 d.wk for 8 wk. High-intensity aerobic interval training resulted in significantly increased VO2max compared with long slow distance and lactate-threshold training intensities (P<0.01). The percentage increases for the 15/15 and 4 x 4 min groups were 5.5 and 7.2%, respectively, reflecting increases in V O2max from 60.5 to 64.4 mL x kg(-1) x min(-1) and 55.5 to 60.4 mL x kg(-1) x min(-1). SV increased significantly by approximately 10% after interval training (P<0.05). : High-aerobic intensity endurance interval training is significantly more effective than performing the same total work at either lactate threshold or at 70% HRmax, in improving VO2max. The changes in VO2max correspond with changes in SV, indicating a close link between the two.

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... Another important factor for aerobic endurance performance [51], along with VȮ 2max , is work efficiency, the ratio between work output and oxygen uptake [52,53]. Physical work conducted less efficiently implies that human locomotion requires more energy and oxygen consumption, resulting in impaired aerobic endurance and poorer physical function during activities of daily living. ...
... Similar to what has been observed in healthy individuals [53] and other patient populations [83,84], endurance training with high aerobic intensity seems to yield greater increases in V O 2peak compared to endurance training with moderate aerobic intensity. In line with this notion, high-intensity aerobic interval training (4-min intervals at ~ 90% of peak heart rate with intermittent active rest periods) was demonstrated to increase pulmonary measured treadmill V O 2peak by 3.1-4.2 ...
... Used with permission from Nygård et al. [54]. other cohorts, such as patients with substance use disorder [86], coronary artery disease [83], and young adults [53]. Although one study failed to document aerobic interval training-induced improvement in V O 2peak with intention-to-treat analyses in people with schizophrenia [87], explorative ad hoc analyses revealed a V O 2peak difference of 4.7 ml kg −1 min −1 after training between subjects instructed by personnel with (2.4 ml kg −1 min −1 increase) or without (2.2 ml kg −1 min −1 decrease) competence in supervising the sessions. ...
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Background Individuals with severe mental disorders (SMDs; schizophrenia spectrum disorders, bipolar disorder, and major depressive disorder) are not only suffering from their mental conditions; they also have an attenuated physical health, augmenting their overall critical condition. Objectives We review and critically appraise the evidence based on (1) key physiological factors relating to aerobic endurance and skeletal muscle strength; (2) implications for physical function and health; and (3) effects of training interventions with different intensities evaluated in individuals with SMDs. Findings Reductions in aerobic endurance factors, peak oxygen uptake (VO2peak) and walking work efficiency, are paralleled by reductions in maximal skeletal muscle strength and power. In turn, the poor aerobic endurance and muscle strength lead to impaired physical function, increased risk of lifestyle-related diseases, and ultimately early death. Exercise has the potential to counteract the attenuated physical health in people with SMDs. While aerobic endurance training is shown to increase VO2peak due to plasticity of the oxygen transport system, strength training is documented to improve maximal muscle strength, power, and walking work efficiency as a result of adaptations in neuromuscular force developing factors. Conclusions In conclusion, improvements in these key determinants for physical health appear to be achievable in people with SMDs despite many being challenged by motivational difficulties with attending regular exercise and have beneficial implications for physical function during activities of daily living, lifestyle-related diseases, and early death.
... In addition to the pre-season soccer training, a continuous running protocol was applied for 45 minutes at 70% of the maximum heart rate (maxHR) of the players immediately after the end of the unit training (24). In long-term jogs applied as additional training, the participants' HR was kept at the desired levels by means of polar watches worn by the participants. ...
... In addition to the pre-season period soccer training in the high-intensity interval training (HIIT) group, a running protocol was applied for 90-95% of the maximum heart rate (maxHR) of the athletes for 15 seconds immediately after the end of the unit training. In 70% of maxHR, a high-intensity interval running protocol was applied with a rest period of 15 seconds, with a total of 8 repetitions, 3 sets and 3 minutes of rest between sets (24). In high-intensity interval runs applied as additional training, the participants' HR was kept at the desired levels by means of polar watches worn by the participants. ...
... These results show us that the groups were formed homogeneously. There is a common view that there is an increase in VO2max values with high-intensity aerobic training (16,20,24). While Mcmillan et al (30) revealed that the increase in VO2max value in each training unit was 0.56% with high-intensity training, Helgerud et al (23) found this rate to be 0.67% in their study. ...
Article
The aim of this study is to examine the effects of different training methods on aerobic performance and respiratory parameters in young soccer players. For this purpose, fourty healthy young male soccer players participated in the study. The mean age of the participants was 16.72± 1.09 years, their average height was 172.45± 5.56 cm and their body weight average was 62.79± 8.91 kg. The study protocol was approved by the Selcuk University Faculty of Sport Sciences Ethics Committee. Different training methods applied in the study were applied in addition to routine training programs 3 times a week for 8 weeks. Fourty soccer players who participated in the study were divided into 5 groups as the control group (CG), small sided games (SSG), transition in SSG (TSSG), high intensity interval training (HIIT) and low intensity continuous training (LICT) groups. Three measurements were made for aerobic performance (VO2max), lactate levels and rating of perceived exertion (RPE). And also, two measurements were applied for respiratory parameters. As a result, significantly increased the VO2max levels of the other groups except the SSG group. LICT significantly decreased lactate levels. RPE were found to be significantly higher in the HIIT in all three measures. It provided significant increases in force vital capacity (FVC) and the forced expiratory volume in 1 second (FEV1) levels of LICT and HIIT groups. There was a significant decrease in the FEV1/FVC levels of the LICT and the peak expiratory flow (PEF) levels of the HIIT. As a result, different trainings applied for eight weeks significantly improved aerobic performance and decreased lactate levels. It resulted in different changes in RPE levels and respiratory parameters. Özet Bu çalışmanın amacı genç futbolcularda farklı antrenman yöntemlerinin aerobik performans ve solunum parametreleri üzerine etkilerini incelemektir. Bu amaçla, çalışmaya sağlıklı 40 genç erkek futbolcu katılmıştır. Katılımcıların yaş ortalamaları 16.72± 1.09 yıl, boy ortalamaları 172.45± 5.56 cm ve vücut ağırlığı ortalamaları 62.79± 8.91 kg olarak tespit edilmiştir. Çalışma protokolü Selçuk Üniversitesi Spor Bilimleri Fakültesi girişimsel olmayan etik kurulu tarafından onaylanmıştır. Çalışmada uygulanan farklı antrenman yöntemleri, 8 hafta boyunca haftada 3 kez rutin antrenman programlarına ek olarak uygulanmıştır. Çalışmaya katılan 40 futbolcu, kontrol grubu, sınırlı alan oyunları (SAO), sınırlandırılmış alanlarda geçiş oyunu (SAGO), yüksek şiddetli interval antrenman (YŞİA) ve
... Even though the total training volume of HIIT sessions is generally considerably lower than that of 'High-Volume (low-intensity) Training' without recovery breaks (<65% of HR max, blood lactate levels < 2 mmol/L, training duration > 30 min), comparative studies often proved similar or even better effects on endurance capacity and maximal oxygen uptake capacity when HIIT sessions were used. These studies were conducted with moderately trained children, teenagers and adults [23][24][25][26][27]. Additionally, highly trained endurance athletes, who predominantly use 'High-Volume low-intensity Training', seem to profit when at least regularly implementing HIIT protocols in their training schedule [24]. ...
... The selection and choice of specific training parameters (duration and number of intervals) when using HIIT protocols seems arbitrary, and there is no gold standard related to training parameters. Several studies found optimal effects of intervals lasting between 2 and 5 min [24,26,29]. Other authors recommend shorter intervals between 15 and 30 s [30,31]. ...
... Peer-reviewed published literature on ultrashort training loads of 5-70 s is currently lacking, and only a few older studies addressed the topic. Helgerud et al. [26] found similar training effects when using 15 s intervals compared to 4 min intervals. ...
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High-Intensity Interval Training (HIIT) promises high training effects on aerobic fitness in children, adolescents and adults in a relatively short time. It is therefore well-established in professional training settings. HIIT methods could also be suited to Physical Education (P.E.) lessons and contribute to students’ health and fitness. Since HIIT sessions need little time and equipment, they can be efficiently implemented in P.E. However, there are few studies which have examined non-running-based HIIT programs in the school sport setting. We therefore conducted an intervention study including 121 students aged 11–15 attending a secondary school in Baden Württemberg, Germany. The effects of three different forms of HIIT training varying in duration and content (4 × 4 HIIT, 12 × 1 HIIT, CIRCUIT) were analyzed. The training was conducted twice a week over 6 weeks (10–12 sessions). Strength and endurance performances were determined in pre- and posttests prior to and after the intervention. Results verified that all three HIIT programs led to significant improvements in aerobic fitness (p < 0.001; part ŋ2 = 0.549) with no significant interaction between time x group. In contrast to the running-based HIIT sessions, CIRCUIT training also led to significant improvements in all of the measured strength parameters. Retrospectively, students were asked to assess their perception of the training intervention. The HIIT sessions were well-suited to students who considered themselves as “athletic”. Less athletic students found it difficult to reach the necessary intensity levels. The evaluation showed that endurance training conducted in P.E. lessons needs a variety of different contents in order to sufficiently motivate students. Students perceiving themselves as “unathletic” may need additional support to reach the required intensities of HIIT. Circuit training sessions using whole-body drills can be efficiently implemented in the P.E. setting and contribute to students’ health and fitness.
... Physical inactivity is one of the leading health problems in the world. Exercise is important for rehabilitation, to enhance health, and for health maintenance, in addition to its role in conditioning for competitive sports [1][2][3]. Robust evidence shows that low levels of cardiorespiratory fitness (CRF) are associated with a high risk of cardiovascular disease and all-cause mortality. CRF, typically assessed by directly measuring maximal oxygen consumption (VO 2max ), is a potentially stronger predictor of mortality than established risk factors such as smoking [4]. ...
... This continued until the participant reached exhaustion after about 5 minutes to 8 minutes. To ensure that VO 2max was reached, the participants were encouraged to continue as long as possible so that a leveling off of VO 2 occurred [1]. A plateau was displayed by all participants at the end of the test, confirming VO 2max . ...
... The HIIT protocol used in Myworkout GO was performed individually on the treadmill, walking or running, and consisted of a 6-minute warm-up at "talking speed." Then, the participants underwent a 4x4-minute interval training (breathing heavy but with no obvious feeling of lactic acid accumulation), interrupted by 3 minutes of active rest periods at "talking speed" between each interval [1]. The 2 HIIT sessions were performed in a supervised setting by an exercise physiologist; however, the exercise itself was guided by the app, with the following instructions: ...
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Background Physical inactivity remains the largest risk factor for the development of cardiovascular disease worldwide. Wearable devices have become a popular method of measuring activity-based outcomes and facilitating behavior change to increase cardiorespiratory fitness (CRF) or maximal oxygen consumption (VO2max) and reduce weight. However, it is critical to determine their accuracy in measuring these variables. Objective This study aimed to determine the accuracy of using a smartphone and the application Myworkout GO for submaximal prediction of VO2max. Methods Participants included 162 healthy volunteers: 58 women and 104 men (17-73 years old). The study consisted of 3 experimental tests randomized to 3 separate days. One-day VO2max was assessed with Metamax II, with the participant walking or running on the treadmill. On the 2 other days, the application Myworkout GO used standardized high aerobic intensity interval training (HIIT) on the treadmill to predict VO2max. Results There were no significant differences between directly measured VO2max (mean 49, SD 14 mL/kg/min) compared with the VO2max predicted by Myworkout GO (mean 50, SD 14 mL/kg/min). The direct and predicted VO2max values were highly correlated, with an R2 of 0.97 (P<.001) and standard error of the estimate (SEE) of 2.2 mL/kg/min, with no sex differences. Conclusions Myworkout GO accurately calculated VO2max, with an SEE of 4.5% in the total group. The submaximal HIIT session (4 x 4 minutes) incorporated in the application was tolerated well by the participants. We present health care providers and their patients with a more accurate and practical version of health risk estimation. This might increase physical activity and improve exercise habits in the general population.
... Health benefits are achieved both through low-to-moderate-and high-intensity training (1)(2)(3)(4). Still, a growing body of knowledge suggests that high-intensity interval training provides larger physiological adaptations in both active recreational adults (2,(5)(6)(7) and patients (2,8). High-intensity interval training stimulate larger physiological adaptations despite considerably less time spent and a lower exercise volume (9). ...
... Given the superior physiological effects of high-intensity training (2,5,8,9), this training should be overall recommended. However, physiological adaptations to exercise rapidly decline when the activity level is not maintained or when participation ceases (12). ...
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Introduction From a public health perspective, it is important to gain more insight into how people can be motivated to maintain effective exercise routines. It is a common belief that moderate-intensity exercise is more pleasant and enjoyable than high-intensity training. This study aims to provide insight into (1) participants' expectations and preferences for training intensity prior to training, (2) how longer-term participation affect participants' experience of endurance training with continuous moderate-intensity training and high-intensity interval training. Materials and methods A total of 22 participants (14 women and eight men) between the ages of 21–30 volunteered for participation. Participants were randomized and divided into two equal groups. A total of 17 participants, nine women and eight men, completed the study. One group did moderate-intensity longer-lasting training and the other did high-intensity interval training. All participants completed three training sessions per week for 8 weeks. Semi-structured interviews were conducted with each participant before and after completing the training intervention. Data was analyzed using thematic analysis. This study is a part of a larger study evaluating and comparing the effects on endurance capacity of high-intensity interval training and moderate-intensity training. Physiological data are previously published. Results The results describe participants expectations prior to training, and how they experienced the actual training. The overall experience of training comprises several factors that work together. Both expectations and actual experiences (e.g., of physical pleasantness or unpleasantness, of positive or negative emotions, and of actual results from the training) contribute to the participants' overall experience of exercise. Conclusion The major finding is that improved physical fitness was a stronger motivator than feelings of pleasantness. Experiencing good results seemed to downplay feelings of unpleasantness and reinforce positive feelings toward exercise. Lack of results reinforce negative feelings toward exercise. Participants reported high-intensity exercise as more unpleasant and exhaustive, but the interval training group were more satisfied and experienced the training as more motivating.
... HIIE protocol was of 4 bouts of 4 minutes (4*4) at 90-95% HRmax with 3 min active recovery at 70% HRmax in accordance with Helgerud et al., 2007. HR max (beats/min) was calculated by the formula: HRmax = 206.9 ...
... We aimed to determine sex-specific effect of high intensity intermittent exercise on the concentration of neurotrophic factors in young adults. For this purpose, 4 sessions of high intensity intermittent exercise for 4 minutes each at intensities between 90-95% of HR max, with 3 minutes of active rest in between the sessions were used (Helgerud et al., 2007) as an intervention of the study. Blood for the assessment of neurotrophic factors and other hormones was extracted before and after the intervention. ...
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The neurophysiological response to exercise on cognition is modulated through chemical pathways which involve several neurotrophic factors and the sex of the individual determines this effect. We examined sex differences in the concentration of neural growth factors (NGF); brain derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF) and insulin like growth factor-I (IGF- I) in response to acute high intensity intermittent exercise (HIIE). We also evaluated the relationship of NGF with gonadal hormones before and after the HIIE session. Forty healthy young adults (22 males and 18 females) performed HIIE (4 bouts of 4 minutes at 90–95% HR max with 3min active recovery at 70% HRmax). Venous blood was drawn before and immediately after the exercise session and was analyzed for the concentration of serum BDNF, VEGF, IGF-I, cortisol, estradiol, luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone, using ELISA method. A significant sex difference (p<0.05) was observed for BDNF concentration in response to HIIE and a significant increase was found in males but not in females. A significant (p<0.005) positive correlation of BDNF with FSH and LH and a significant (p<0.05) negative correlation of BDNF and VEGF with testosterone were found. Other NGFs (VEGF and IGF-I) did not show sex differences in response to HIIE. In conclusion, a single session of HIIE increases the serum concentration of BDNF in males and IGF-I in females and the response of NGF is different in males and females.
... The understanding that exercise intensity is a potent stimuli for improving VO 2max is not a new discovery [27][28][29][30]. To these ends, HIIT is generally considered a more potent stimulus than moderate-intensity continuous training (MICT) for improving VO 2max (especially over a short intervention duration) [23,25,[31][32][33]. In this context, a recent meta-analysis by Su and colleagues [25] indicated that HIIT in normoxia increased VO 2max more than MICT in normoxia, in overweight/obese individuals (aged 18-48 years), specifically when intervals were >2 min in duration, with a standard mean difference of 0.444 (95% confidence intervals [CI] = 0.037-0.851; ...
... Small magnitude of effect). Moreover, a seminal RCT [33] observed greater improvement in VO 2max following 4 × 4 min running with 3 min rests (Cohen's d = 0.66) and 47 × 15 s of running with 15 s rests (Cohen's d = 0.79) at 90-95% heart rate maximum compared to lactate threshold (Cohen's d = 0.16) and sub-threshold training (Cohen's d = 0.13). ...
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The present study aimed to determine the effect of high intensity interval training (HIIT) in hypoxia on maximal oxygen uptake (VO2max) compared with HIIT in normoxia with a Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)-accordant meta-analysis and meta-regression. Studies which measured VO2max following a minimum of 2 weeks intervention featuring HIIT in hypoxia versus HIIT in normoxia were included. From 119 originally identified titles, nine studies were included (n = 194 participants). Meta-analysis was conducted on change in (∆) VO2max using standardised mean difference (SMD) and a random effects model. Meta-regression examined the relationship between the extent of environmental hypoxia (fractional inspired oxygen [FiO2]) and ∆VO2max and intervention duration and ∆VO2max. The overall SMD for ∆VO2max following HIIT in hypoxia was 1.14 (95% CI = 0.56–1.72; p < 0.001). Meta-regressions identified no significant relationship between FiO2 (coefficient estimate = 0.074, p = 0.852) or intervention duration (coefficient estimate = 0.071, p = 0.423) and ∆VO2max. In conclusion, HIIT in hypoxia improved VO2max compared to HIIT in normoxia. Neither extent of hypoxia, nor training duration modified this effect, however the range in FiO2 was small, which limits interpretation of this meta-regression. Moreover, training duration is not the only training variable known to influence ∆VO2max, and does not appropriately capture total training stress or load. This meta-analysis provides pooled evidence that HIIT in hypoxia may be more efficacious at improving VO2max than HIIT in normoxia. The application of these data suggest adding a hypoxic stimuli to a period of HIIT may be more effective at improving VO2max than HIIT alone. Therefore, coaches and athletes with access to altitude (either natural or simulated) should consider implementing HIIT in hypoxia, rather than HIIT in normoxia where possible, assuming no negative side effects.
... In the last few years, a large number of studies have been published which have shown positive effects of HIIT on aerobic power in children and adults. Positive effects are shown especially in maximum oxygen uptake (VO 2max ), power at the ventilator thresholds (VT1 and VT2) and power at the lactate threshold (Engel, Ackermann, Chtourou & Sperlich, 2018;Esfarjani & Laursen, 2007;Helgerud et al., 2007;Laursen, Blanchard & Jenkins, 2002). In artistic gymnastics, HIIT as a training method for aerobic power has become a greater focus of attention (Salagas, Donti, Katsikas & Bogdanis, 2020). ...
... The lack of improvement in VO 2peak after HIIT in this study contradicts the results of Schoenmakers et al. (2016) who demonstrated an increase in VO 2peak after HIIT. An increase in VO 2peak after HIIT has also been shown in studies on the cycle ergometer or treadmill (Edge et al., 2006;Helgerud et al., 2007). One reason for the lack of increase in VO 2peak can be seen in the difference in VO 2 uptake kinetics between upper and lower body exercise. ...
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Problem Statement. While there is an agreement on specific endurance training for typical endurance sports such as running, swimming and cycling, there is a need for discussion for sports with short-term high-intensity exercise like artistic gymnastics. Purpose. The aim of this study was to investigate the effects of gymnastics-specific high intensity interval training on endurance performance on the pommel horse and the arm ergometer. Materials and methods. Endurance performance on the pommel horse was determined by the maximum number of circles, endurance performance on the arm ergometer by peak power and power at the ventilatory thresholds 1 and 2. In addition, the effect on oxygen uptake, peak blood lactate concentration and peak heart rate on the pommel horse and arm ergometer should be investigated. Eleven gymnasts (age: 15.27 ± 2.49 years; weight: 55.5 ± 12.8 kg; height: 163.5 ± 12.2 cm) from a local gymnastics club performed high intensity interval training 2 times per week for 4 weeks. The high intensity interval training consisted of ten 40 s intervals (2 x 5 upper body exercises with 90% of the maximum heart rate) and a rest period of 60 s between each interval. Results. The maximum number of circles (56.0 to 66.5), peak power (160.5 to 194.5 W), power at the ventilatory thresholds 1 (79.0 to 104.5 W) and power at the ventilatory thresholds 2 (132.5 to 156.0 W) increased significantly from pre-to post-test. Peak oxygen uptake shows a significant decrease on the arm ergometer (47.2 to 43.1 ml/min/kg), but no significant change on the pommel horse (42.9 to 43.2 ml/min/kg). Peak blood lactate concentration and peak heart rate show no change from pre to post test on the pommel horse and arm ergometer. Conclusions. The results of the study show that gymnastics-specific high intensity interval training is a time-efficient training method for improving upper body and pommel horse-specific endurance performance.
... Reducing body fat mass may mitigate the likelihood of developing cardiorespiratory disease and diabetes, as adipose tissue is a precursor to these conditions [57]. Central (increased stroke volume) and peripheral adaptations (increased capillary density and mitochondrial adaptation) may be responsible for the increase in cardiorespiratory fitness elicited by high-intensity exercise [58][59][60]. Therefore, once medically cleared to undertake regular PA, exoskeleton walking may enable individuals with neurological impairments to exercise at a high intensity, and promote more favourable cardiorespiratory fitness and body composition adaptations than an arm crank or wheelchair ergometer can, as exoskeleton walking may elevate thoracohumeral and trunk muscle mass activation rather than isolating the upper extremities [14]. ...
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Individuals with neurological impairments tend to lead a predominantly sedentary lifestyle due to impaired gait function and mobility. This may be detrimental to health by negatively impacting cardiorespiratory fitness and muscular strength, and increasing the risk of developing secondary health problems. Powered exoskeletons are assistive devices that may aid neurologically impaired individuals in achieving the World Health Organisation’s (WHO) physical activity (PA) guidelines for health. Increased PA should elicit a sufficient cardiorespiratory stimulus to provide health benefits to exoskeleton users. This study examined the cardiorespiratory demands of treadmill walking with and without the Ekso GT™ among able-bodied participants. The Ekso GT™ is a powered exoskeleton that enables individuals with neurological impairments to walk by supporting full body mass with motors attached at the hip and knee joints to generate steps. This feasibility study consisted of one group of healthy able-bodied individuals (n = 8). Participants completed two 12 min treadmill walking assessments, one with and one without the Ekso GT™ at the same fixed speed. Throughout each walking bout, various cardiorespiratory parameters, namely, volume of oxygen per kilogram (kg) of body mass (V˙O2·kg−1), volume of carbon dioxide per kg of body mass (V˙CO2·kg−1), respiratory exchange ratio (RER), ventilation (V˙E), heart rate (HR), and rate of perceived exertion (RPE), were recorded. Treadmill walking with Ekso GT™ elevated all recorded measurements to a significantly greater level (p ≤ 0.05) (except RER at 1 km·h–1; p = 0.230) than treadmill walking without the Ekso GT™ did at the same fixed speed. An increased cardiorespiratory response was recorded during treadmill walking with the exoskeleton. Exoskeleton walking may, therefore, be an effective method to increase PA levels and provide sufficient stimulus in accordance with the PA guidelines to promote cardiorespiratory fitness and subsequently enhance overall health.
... Each bout is interspersed by a 3 min active resting period performing at 70% of HR max . 54 The session will end with a 5 min cool-down period of low-intensity workload. Total treadmill time per session is 40 min. ...
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Introduction Patients with substance use disorder (SUD) have high prevalence of lifestyle-related comorbidities. Physical exercise is known to yield substantial prophylactic impact on disease and premature mortality, and there seems to be an inverse association between physical fitness and adverse health outcomes. High-intensity training is regarded as most effective for improving physical fitness, but less is known concerning the ideal training dose necessary to achieve clinically relevant effects in these patients. The aim of this study is to compare the effect of low-dose and high-dose, high-intensity training, on physical fitness in patients diagnosed with SUD. Methods and analysis This study will recruit 40 in-patients of mixed genders, aged 18–70 years. Participants will be block allocated to low-dose or high-dose training, encompassing 24 high-intensity interval and maximal strength training sessions (3/week × 8 weeks). After a 10 min warm-up, the low-dose group will perform 1×4 min intervals at ⁓90% of maximal heart rate and 2×4 repetitions strength training at ⁓90% of 1 repetition maximum. The high-dose group will perform 4×4 min intervals at ⁓90% of maximal heart rate and 4×4 repetitions strength training at ⁓90% of 1 repetition maximum. Clinical measurements and physical tests will be conducted at baseline, midway and on completion and a questionnaire on physical activity will be administered at baseline. Ethics and dissemination This protocol is in accordance with the Standard Protocol Items: Recommendations for Interventional Trials statement. All participants will sign a written informed consent. The Regional Committee of Medical Research Ethics, Norway has approved the study. A study of this kind is warranted, and the results will be published in an open access journal to ensure public access, and presented at national and international conferences. Trial registration number NCT04065334 .
... High-intensity interval training (HIIT) has been documented as a safe and effective training method for cardiac rehabilitation [21]. HIIT can be defined as a short burst of maximal effort interspersed by a few minutes of rest or active recovery, and it has been reported to be more effective than CMT for improving cardiorespiratory fitness in different populations [16][17][18][22][23][24]. HIIT, which consists of several bouts of high-intensity exercise (85-95% of HRmax) lasting 1 to 4 min interspersed with intervals of rest or active recovery [15,17,18], has been found to improve endothelial function and its markers [16,18], insulin sensitivity [18], markers of sympathetic activity [16,17], arterial stiffness [15,16], blood glucose and lipoproteins [18]. ...
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The likelihood of pre-hypertensive young adults developing hypertension has been steadily increasing in recent years. Despite the fact that aerobic exercise training (AET) has demonstrated positive results in lowering high blood pressure, the efficacy of different types of AET among pre-hypertensive young adults has not been well-established. The objective of this study was to evaluate the effectiveness of high-intensity interval training (HIIT) and continuous moderate-intensity training (CMT) on the blood pressure (BP) of physically inactive pre-hypertensive young adults. In total, 32 adults (age 20.0 ± 1.1 years and BMI 21.5 ± 1.8) were randomly assigned to three groups: HIIT, CMT and control (CON). The HIIT and CMT groups participated in 5 weeks of AET, while the CON group followed a DASH diet plan only. The HIIT protocol consisted of a 1:4 min work to rest ratio of participants, at an 80–85% heart rate reserve (HR-reserve) and a 40–60% HR-reserve, respectively, for 20 min; the CMT group exercised at 40–60% of their HR-reserve continuously for 20 min. In both the HIIT and CMT groups, systolic blood pressure (SBP) (3.8 ± 2.8 mmHg, p = 0.002 vs. 1.6 ± 1.5 mmHg, p = 0.011) was significantly reduced, while significant reductions in the diastolic blood pressure (DBP) (2.9 ± 2.2 mmHg, p = 0.002) and mean arterial pressure (MAP) (3.1 ± 1.6 mmHg, p < 0.0005) were noted only in the HIIT group. No significant differences in SBP (−0.4 ± 3.7 mmHg, p = 0.718), DBP (0.4 ± 3.4 mmHg, p = 0.714), or MAP (0.1 ± 2.5 mmHg, p = 0.892) were observed in the CON group. Both HIIT and CMT decreased BP in physically inactive pre-hypertensive young adults; however, HIIT yielded more beneficial results in terms of reducing the SPB, DBP and MAP.
... be defined more generally as a combination of periods in which high-intensity load (load interval = LI) alternate with low-intensity exercise or passive rest, the so-called rest interval (RI) or inactive phase (Gibala et al., 2006;Helgerud et al., 2007;. High intensity in the active phase is key to the effectiveness of the method and has been discussed by many experts. ...
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... Studies investigating the relationship between PA and psychotropics use have showed a reduced risk of purchasing psychotropics by increasing physical activity levels with the lowest risk among those showing PA pattern of moderate to vigorous intensity of high volume [23]. The latter finding indicate that intensity could be an important PA dimension for psychotropics reduction and is also shown to be a key factor to increase VO 2peak [34,35] . ...
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Background The use of psychotropics is high among the older population and may have detrimental effects on their physical and mental health. Cardiorespiratory fitness (CRF) is a strong and modifiable measure of health and declines with age. We aimed to study the association of change in CRF with use of psychotropics in community-dwelling older adults. Methods We analyzed longitudinal data from 1531 older adults from the Generation 100 study, aged 70–77 years at inclusion, and with a permanent address in Trondheim, Norway. Data on objectively measured peak oxygen uptake (VO 2peak ) were linked with register data from the Norwegian Prescription Database on prescribed psychotropics. The included psychotropics were antidepressants (N06A), antipsychotics (N05A), anxiolytics (N05B), hypnotics and sedatives (N05C), and N03AE (benzodiazepine derivatives). Analyses were done on any psychotropics as one group, and on the following separate groups: antidepressants (N06A), benzodiazepines (N05BA, N05CD, and N03AE), and z-hypnotics (N05CF). Peak oxygen uptake was measured four times over a five-year period and corresponding medication use was measured as defined daily doses (DDD). A random effects estimator was applied to investigate the association of change in VO 2peak with the use of psychotropics. Results We found a statistically significant curvilinear association of change in VO 2peak with use of any psychotropics and antidepressants. For VO 2peak up to ~ 40 ml/kg/min, each 1 ml/kg/min increase was associated by a 3.3 DDD and 2.5 DDD decrease in use of any psychotropics and antidepressants, respectively. A bottoming-out effect was found and increases in VO 2peak above ~ 40 ml/kg/min showed increased use of any psychotropics and antidepressants. However, the association of change in VO 2peak with use was stronger for changes in the lower continuum of VO 2peak levels and decreased with increasing VO 2peak . No statistically significant association of change in VO 2peak with use of benzodiazepines and z-hypnotics were found. However, because of a non-randomized design, we cannot rule out the possibility of confounding by indication. Conclusions The results of this study show a curvilinear association of change in VO 2peak with use of any psychotropics and antidepressants in older adults. This relationship adds a new viewpoint on the adverse effects of psychotropic use and should be considered in interventions and policies aimed at reducing psychotropic medication use among the older population.
... One of them is High-Intensity Interval Training (HIIT), a combination of highintensity and low-intensity physical training (6,7). Recent studies have shown that HIIT improves body composition (8,9) and cardiopulmonary fitness (10)(11)(12). ...
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Background. Continuous Training (CT) is often considered an effective way to reduce obesity. However, recently, a popular protocol called High-Intensity Interval Training (HIIT) has shown up as an alternative to CT. There is another factor affecting obesity named UCP2 45-bp Insersion/Deletion genetic marker. Objectives. This research aims to determine the effect of the UCP2 45-bp I/D gene as a genetic marker in response to obese training (CT and HIIT). Methods. This study was a randomized controlled trial (RCT) in two cycling training groups (CT and HIIT). The purposive sampling method was used to collect 28 women with obesity (BMI≥25 kg/m2). Random allocation into two groups using the block randomization method. Exercise training interventions were conducted for 12 weeks, with a frequency of 3 times per week. Results. Body composition data (body weight, BMI, and Body Fat Percentage) before and after the intervention were analyzed with the Dependent T-Test and found that both the CT and HIIT groups had significant improvements in body composition (P<0.05). ANCOVA Test analyzed the effect of training type and UCP2 45-bp I/D variance on body composition. There was no effect of training type and genetic variation on body weight improvement (P=0.145), body mass index improvement (P=0.153), and body fat improvement (P=0.159). Conclusion. Both Continuous and High-Intensity Interval Training can equally improve the body composition of obese patients. There was no UCP2 45-bp I/D variance effect on the response to training in a woman with obesity.
... HIIT has been the subject of several clinical studies, showing improvements in metabolic [6], physical [7,8] and cognitive [9] levels within a variety of groups of patients. The maximum rate of oxygen consumption (VO 2 peak) in HIIT is significantly higher than in MCT [10][11][12][13]. ...
Article
Background With an increasing number of inpatients in geriatric rehabilitation, there is continuing interest in efficient training measures regarding physical performance.Objectives To examine the feasibility and outcomes of high-intensity interval training (HIIT) in geriatric patients. Methods Single-centre randomized controlled study of HIIT vs. moderate continuous training (MCT) for patients ≥65 years old referred to inpatient rehabilitation. Cardiopulmonary exercise testing (CPET) was performed before the first and last training in order to measure participant’s cardiorespiratory fitness. At the same time-points patients completed a series of questionnaires regarding subjective improvements and acceptance of the training methods. Results Regarding feasibility, HIIT showed a completion rate of 82.4% and an adherence rate of completed sessions of 83.3%. HIIT significantly improved cardiorespiratory fitness (+13% for VO2peak, p=0.01), respiratory quotient (+9%, p=0.01) and power output (+12% for Watt peak, p=0.01) compared with MCT. Significant improvements were also seen over time for physical and mental scores of PROMIS-10 and quality of life. Conclusion A HIIT intervention has proven feasible for elderly patients in a geriatric rehabilitative setting. Further research should specify the HIIT intervention in order to offer this training to more patients. Long-term observations are also needed.
... Notably, the term HIIT is not consistently defined, and multiple descriptions and exercise protocols are used [15]. In the current literature, a range of protocols are employed, which consist of exercise bouts lasting a few seconds and intensities close to maximum [16] and bouts lasting up to 4 min and correspondingly lower intensities [17,18]. The differences in the training variables are expected to reflect changes in the metabolism and adaptations of organic systems [19]. ...
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In light of the global physical inactivity pandemic, the increasing prevalence of non-committable diseases, and mounting healthcare costs, effective and feasible prevention and treatment approaches are urgently needed [...]
... High-intensity interval training (HIIT) has been documented as a safe and effective training method for cardiac rehabilitation [21]. HIIT can be defined as a short burst of maximal effort interspersed by a few minutes of rest or active recovery, and it has been reported to be more effective than CMT for improving cardiorespiratory fitness in different populations [16][17][18][22][23][24]. HIIT, which consists of several bouts of high-intensity exercise (85-95% of HRmax) lasting 1 to 4 min interspersed with intervals of rest or active recovery [15,17,18], has been found to improve endothelial function and its markers [16,18], insulin sensitivity [18], markers of sympathetic activity [16,17], arterial stiffness [15,16], blood glucose and lipoproteins [18]. ...
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The likelihood of pre-hypertensive young adults developing hypertension has been steadily increasing in recent years. Despite the fact that aerobic exercise training (AET) has demonstrated positive results in lowering high blood pressure, the efficacy of different types of AET among pre-hypertensive young adults has not been well-established. The objective of this study was to evaluate the effectiveness of high-intensity interval training (HIIT) and continuous moderate-intensity training (CMT) on the blood pressure (BP) of physically inactive pre-hypertensive young adults. In total, 32 adults (age 20.0 ± 1.1 years and BMI 21.5 ± 1.8) were randomly assigned to three groups: HIIT, CMT and control (CON). The HIIT and CMT groups participated in 5 weeks of AET, while the CON group followed a DASH diet plan only. The HIIT protocol consisted of a 1:4 min work to rest ratio of participants, at an 80–85% heart rate reserve (HR-reserve) and a 40–60% HR-reserve, respectively, for 20 min; the CMT group exercised at 40–60% of their HR-reserve continuously for 20 min. In both the HIIT and CMT groups, systolic blood pressure (SBP) (3.8 ± 2.8 mmHg, p = 0.002 vs. 1.6 ± 1.5 mmHg, p = 0.011) was significantly reduced, while significant reductions in the diastolic blood pressure (DBP) (2.9 ± 2.2 mmHg, p = 0.002) and mean arterial pressure (MAP) (3.1 ± 1.6 mmHg, p < 0.0005) were noted only in the HIIT group. No significant differences in SBP (−0.4 ± 3.7 mmHg, p = 0.718), DBP (0.4 ± 3.4 mmHg, p = 0.714), or MAP (0.1 ± 2.5 mmHg, p = 0.892) were observed in the CON group. Both HIIT and CMT decreased BP in physically inactive pre-hypertensive young adults; however, HIIT yielded more beneficial results in terms of reducing the SPB, DBP and MAP.
... At the third visit, 2 weeks after the ST session, the participants took part in a HIIT session on a treadmill, as previously described (35). The participants were offered two packs of energy gel before this session. ...
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Context: Exercise is recognized as an important strategy to prevent bone loss, but its acute effects on bone turnover markers (BTMs) and related markers remain uncertain. Objective: To assess the acute effects of two different exercise modes on BTMs and related markers in young adults of both sexes and elderly men. Design, Setting, Participants: This was a three-group crossover within-subjects design study with a total of 53 participants—19 young women (aged 22–30), 20 young men (aged 21–30 years), and 14 elderly men (aged 63–74 years)—performing two different exercise sessions [strength training (ST) and high-intensity interval training (HIIT)] separated by 2 weeks, in a supervised laboratory setting. Main Outcome Measures: Plasma volume-corrected serum measurements of the BTMs C-terminal telopeptide of type 1 collagen (CTX-I) and procollagen of type 1 N-terminal propeptide (P1NP), total osteocalcin (OC), sclerostin, and lipocalin-2 (LCN2) at baseline, immediately after, and 3 and 24 h after each of the two exercise modes were performed. Results and Conclusion: Analyses revealed sex- and age-dependent differences in BTMs and related bone markers at baseline and time-, sex-, and age-dependent differences in response to exercise. No differences between exercise modes were observed for BTM response except for sclerostin in young men and LCN2 in elderly men. An acute, transient, and uniform increase in P1NP/CTX-1 ratio was found in young participants, demonstrating that beneficial skeletal effects on bone metabolism can be attained through both aerobic endurance and resistance exercise, although this effect seems to be attenuated with age. The acute effects of exercise on bone-related biomarkers were generally blunted after 24 h, suggesting that persistent alterations following prolonged exercise interventions should be assessed at later time points.
... However, HIIT proved to have a more significant effect than traditional aerobic training on VȮ2max (p<0.02). These results are consistent with recent studies, which have found that "high-intensity aerobic interval training resulted in significantly increased VȮ2max compared with long slow distance and lactate-threshold training intensities (P <0.01)" [43]. ...
Article
Today, more than 20% of the world's population suffers from hypertension, a major risk factor for heart disease. Therefore, lifestyle modifications such as dietary change, smoking cessation, and exercise are often prescribed to hypertensive patients as a first-line treatment. This study aims to examine and compare the effects of different exercise regimens on the cardiovascular system, particularly that of high-intensity interval training (HIIT) and lower-to-moderate-intensity aerobic exercise (aka aerobic exercise). After researching various databases and extracting 4,724 studies, 196 were viable within the exclusion criteria related to exercise's effects on blood pressure and maximal oxygen uptake (V̇O2max). Of these, 36 studies were selected as viable, and their data is herein outlined. In addition, the results provided by these studies were summarized, respectively, and the raw data were analyzed using a two-tailed unpaired t-test. Through this study, we aim to clarify whether HIIT or lower-to-moderate-intensity aerobic exercise differ in their effects on improving cardiovascular health. It was observed that HIIT was non-inferior to lower-to-moderate-intensity aerobic exercise in the reduction of ambulatory blood pressure of hypertensive or normotensive individuals. However, HIIT was more effective at increasing cardiorespiratory fitness by means of V̇O2max than aerobic exercise was. Considering the significant time-to-completion difference between both exercise modalities, it is remarkable that HIIT has the same benefits as lower-to-moderate-intensity aerobic exercise on blood pressure and higher efficiency in increasing V̇O2max.
... Blood pressure was not affected by exercise training. Family physician according, Helgerud et al., (2007) studied effect of high intensity (90-95% HRmax) and moderate intensity (70-85% HRmax) exercises on VO2max in 40 healthy, physically active and non-smoking subjects. The subjects exercised three times a week for eight weeks. ...
... 22 HIIT can be defined as a short burst of maximal effort interspersed by a few minutes of rest or active recovery, and it has been reported to be more effective than CMT for improving cardiorespiratory fitness in different populations. [16][17][18][23][24][25] HIIT that consists of several bouts of high-intensity exercise (~85% to 95% of HRmax) lasting 1 to 4 minutes interspersed with intervals of rest or active recovery 15,17,18 has been found to improve endothelial functions and its markers 16,18 insulin sensitivity, 18 markers of sympathetic activity, 16,17 arterial stiffness, 15,16 blood glucose and lipoproteins. 18 The purpose of this study was to determine the effects of HIIT and CMT on the BP of physically inactive prehypertensive young adults and also to determine which type of training is more efficient in lowering the SBP and DBP of this population. ...
Preprint
The likelihood of a pre-hypertensive young adult to develop hypertension has been steadily increasing over the past few years. Aerobic exercise training (AET) has been found to reduce high blood pressure, however, efficacy of different types of aerobic exercise is yet to be determined among the pre-hypertensive young adults. The objective of this study was to evaluate the effectiveness of high-intensity interval training (HIIT) and continuous moderate-intensity training (CMT) on blood pressure (BP) in young physically inactive pre-hypertensive adults. 32 adults (age 20.0±1.1) were randomly assigned into 3 groups; HIIT, CMT, and control (CON). HIIT and CMT groups participated in 5 weeks of AET with CON group not participating in any exercise. The HIIT protocol consisted of 1:4 minute work to rest ratio of participants 80%-85% heart rate reserve (HR-reserve) and 40%-60% HR-reserve respectively for 20 minutes, CMT group exercised at 40%-60% of HR-reserve continuously for 20 minutes. In both HIIT and CMT groups, systolic blood pressure (SBP) (3.8±2.8 mmHg, P=0.002 VS 1.6±1.5 mmHg, P=0.011) was significantly reduced. While, significant reductions were noted in the diastolic blood pressure (DBP) (2.9±2.2 mmHg, P=0.002) and mean arterial pressure (MAP) (3.1±1.6mmHg, P<0.0005) only in the HIIT group. No significant difference in SBP (-0.4±3.7 mmHg, P=0.718), DBP (0.4±3.4 mmHg, P=0.714), or MAP (0.1±2.5mmHg, P= 0.892) was observed in the CON group. Both HIIT and CMT decreased the BP in physically inactive pre-hypertensive young adults; however, HIIT yielded more beneficial results in terms of reducing the SPB, DBP, and MAP.
... The magnitude of the reported increase in absolute V O2max should also be contextualized against other controlled interventions of similar duration. For instance, untrained subjects undertaking eight weeks of endurance exercise training exhibited increases in V O2max in the region of 7 -18% [1][2][3][4], while 11 weeks administration of erythropoietin (EPO)a potent stimulus for red blood cell production, widely utilized as a doping agent in endurance sport -improved V O2max in untrained subjects by 12% [5]. Moreover, the increase in V O2max reported by Medeiros et al. is ~3-fold greater than would be anticipated given the documented association between serum vitamin D concentrations and cardiorespiratory fitness [6]. ...
... And aerobic exercise was defined as a target heat rate reaching to 70% of the HR max . [25] Inclusion criterion: P: population was comprised of adult patients with episodic migraine or TTH; I: studies evaluated neuromodulation, aerobic exercise, or acupuncture; C: control group involved usual care, wait list, routine care, sham stimulation/acupuncture, or no treatment; O: studies included outcomes of interest; S: the studies were RCTs; articles were written in English or Chinese. We also ensured that each study's definition of migraine and TTH matched the International Classification of Headache Disorders, 2nd or 3rd. ...
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... The authors also highlight that it is important to improve the already mentioned methodologies together in a balanced way to reach the highest possible level of performance. Helgerud and his colleagues [26] analyzed the impact of different endurance-improving methods on university students three times a week for 8 weeks. They found that HIIT resulted in better oxygen intake than continuous methods. ...
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Data measured in the U15–U19 age groups at the football academy were analyzed during the research (N = 70). These data comprised Body Mass, Height, YYIR1, 30 m running, FMS, and SLJ, Locomotor parameters using the 6-week averages of Catapult OptimEye S5, mechanical performance parameters. The players did well in the motoric tests: YYIR1 (M = 2155, SD = 311), 30 m (M = 4.34, SD = 0.26), and SLJ (M = 2.28, SD = 0.18), and the different age groups underwent dynamic improvement. The young soccer players ran 19,552m players ran 568, 298, and 97 m in the moderate-, high-, and sprint-intensity zones. The athletes’ maximum speed was M = 26.72 km/h (SD = 1.74). The differences between the age groups were justified statistically in each case.
... In addition to duration, physical activity guidelines suggest children accrue a variety of intensities in their movements throughout the day, with greater amounts of energetic play being best for children's health and development (World Health Organization, 2019). For instance, walking or stretching is good for restoring attention (Bailey et al., 2018) whereas higher intensities like running and jumping jacks protect heart health and reduce feelings of anxiety and depression (Helgerud et al., 2007;Rebar et al., 2015). The continuum of intensity ranges from standing to light walking to higher intensities in the "huff and puff" category that result in a higher heart rate or get children out of breath. ...
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Self-regulation is a critical emergent developmental competency that lays the foundation for children’s later psychosocial health and academic achievement. Recent work indicates that physical activity and energetic play opportunities support children’s self-regulation in the early childhood classroom. Many early childhood programs offer opportunities for children to engage in play, but teachers are rarely seen modeling physically active behaviors and face barriers to integrating opportunities for energetic play with early academic skills. Early childhood educational settings hoping to support children’s self-regulation development can provide multiple opportunities for children to observe teachers modeling physical activity, provide teacher support and scaffolding for physically active learning centers, and engage children in meaningful energetic play while promoting a range of academic skills. This article provides 10 research-based guidelines for supporting children’s self-regulation development through physical activity in early childhood classrooms.
... During intense physical training, physical stress and homeostasis alterations occur when the body exceeds 60% of the maximal oxygen consumption (VO 2max ) or if the duration of the exercise exceeds 90 min (even when the intensity does not exceed 40% VO 2max ), leading to activation of the HPA axis [89,90]. Similarly, in the precompetition periods, athletes face high levels of psychological stress that also trigger the HPA axis with similar consequences on the microbiota profile. ...
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Gut microbiota refers to those microorganisms in the human digestive tract that display activities fundamental in human life. With at least 4 million different bacterial types, the gut microbiota is composed of bacteria that are present at levels sixfold greater than the total number of cells in the entire human body. Among its multiple functions, the microbiota helps promote the bioavailability of some nutrients and the metabolization of food, and protects the intestinal mucosa from the aggression of pathogenic microorganisms. Moreover, by stimulating the production of intestinal mediators able to reach the central nervous system (gut/brain axis), the gut microbiota participates in the modulation of human moods and behaviors. Several endogenous and exogenous factors can cause dysbiosis with important consequences on the composition and functions of the microbiota. Recent research underlines the importance of appropriate physical activity (such as sports), nutrition, and a healthy lifestyle to ensure the presence of a functional physiological microbiota working to maintain the health of the whole human organism. Indeed, in addition to bowel disturbances, variations in the qualitative and quantitative microbial composition of the gastrointestinal tract might have systemic negative effects. Here, we review recent studies on the effects of physical activity on gut microbiota with the aim of identifying potential mechanisms by which exercise could affect gut microbiota composition and function. Whether physical exercise of variable work intensity might reflect changes in intestinal health is analyzed.
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Background and Aim: The prevalence of obesity is recognized as a health problem worldwide. Metabolic syndrome as the most important obesity factor is considered as one of the health problems in all societies. Supportive and complementary interventions are considered improvements in the status of individuals with metabolic syndrome. Therefore, the aim of this study was to investigate the effects of eight weeks of sodium alginate supplementation and high intensity interval training on lipid profiles and liver enzymes in metabolic syndrome women. Materials and Methods: Thirty women with metabolic syndrome were randomly assigned into 4 groups: intermittent exercise (High Intensity Interval Training)+supplement (n=9), intermittent exercise (HIIT) )n=8), complementary (n=7) and control group (n=6). Subjects in HIIT and HIIT + supplementation groups performed three sessions of intermittent exercise each week for eight weeks with an intensity of 85% to 95% of the maximum heart rate. Sodium alginate supplementation was taken three times a week and 30 minutes before meals in the amount of 1.5 g of sodium alginate dissolved in 100 mg of water. Blood sampling were taken from all 4 groups 48 hours before and after the exercise program. One-way ANOVA and t-test were used for data analysis (P≤0.05). Results: The results showed that in the exercise+supplement group lipid profile (P=0.005) and aspartate aminotransferase (P=0.012)(17.8%), fat percentage (P=0.001)(9.7%), BMI (P=0.000) and alanine aminotransferase (P=0.035)(12.7%) compared to the other group were significantly reduced, indicating the effect of intermittent exercise and supplementation on improving the symptoms of metabolic syndrome in women participating in this study. Conclusion: According to the results of this study, it seems that high intensity intermittent exercise with sodium alginate supplementation can be effective in prevention of some obesity related diseases and treatment of the metabolic syndrome
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The present investigation examined the acute effects of high-intensity interval exercise (HIIE) on temporal changes in behavioral and neuroelectrical indices of working memory. Young adults (n = 22) performed a visual working memory change detection task of equiprobable 2- to 5-dot set sizes while contralateral delay activity (CDA) and N2pc ERP components were assessed at three consecutive time periods (40-min, 54-min, and 68-min) following three separate counterbalanced 9-min sessions of seated rest, HIIE-aerobic (treadmill intervals of moderate- and high-intensity run/walk periods) and HIIE-aerobic/resistance (intervals of rest and body-weight calisthenics). Behavior results revealed greater 4-dot accuracy for HIIE-aerobic/resistance compared to seated rest only at 40-min, maintenance of 5-dot accuracy across time for HIIE-aerobic compared to HIIE-aerobic/resistance and seated rest, and greater temporal stability in overall accuracy performance (i.e., inter-class correlation between temporally adjacent assessments) for both HIIE conditions compared to seated rest. CDA and N2pc results revealed no change in amplitude across time and between HIIE-aerobic, HIIE-aerobic/resistance, and seated rest. However, greater temporal stability in CDA amplitude was observed for HIIE-aerobic compared to seated rest. These findings suggest that short bouts of HIIE may serve as an effective modality for improvements and temporal stabilization in behavior with some evidence for stabilization of neuroelectrical indices of working memory capacity. Together, these data broadly suggest that short acute bouts of exercise may facilitate improvements in underlying mental operations responsible for temporal stability in cognitive and neurocognitive function.
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The purpose of this case study was to examine the short-term development of performance and aerobic endurance following prolonged low-intensity ski trekking (LIST) in an Arctic region. Two male recreational athletes (aged 24 and 26 years) with high aerobic fitness performed LIST 7 ± 2 h·day ⁻¹ for 23 consecutive days, while hauling sledges (∼80 kg initially) with supplies from the north to the south of Svalbard (∼640 km). Time to exhaustion, maximal oxygen uptake (V̇O 2max ), lactate threshold (LT) and work economy were evaluated at pre- and post-trek. The results showed that the absolute and relative exercise intensity during LIST were ∼3.9 km·h ⁻¹ and ∼60% of maximal heart rate, respectively. Time to exhaustion during a ∼4–6 min ramp walking test, and a >45 min stepwise walking test, while pulling 12.5 kg weights (simulation of ski trekking with loaded sledge), increased by 11–17% and 3–9%, respectively, following LIST. Body mass and V̇O 2max relative to body mass (ml·kg ⁻¹ ·min ⁻¹ ) decreased by 5–8% and increased by 3–8%, respectively. Furthermore, the workload associated with LT and LT percentage of V̇O 2max increased by 39–69% and 12–13%, respectively. No notable change in work economy was observed. The mean pace during LIST (∼3.9 km·h ⁻¹ ) corresponded to the treadmill walking speed (4 km·h ⁻¹ ) with the lowest oxygen cost (mL·kg ⁻¹ ·m ⁻¹ ) in both participants. It can be concluded that short-term prolonged LIST can improve ski trek-simulated performance and fractional utilisation of V̇O 2max in recreational athletes with high aerobic fitness. Moreover, highly aerobically fit ski trekkers appear to instinctively choose the most energy-efficient pace during LIST.
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Introduction: High-intensity interval training (HIIT) and sprint interval training (SIT) significantly increase maximal oxygen uptake (V̇O2max) which enhances endurance performance and health status. Whether this response is due to increases in central cardiovascular function (cardiac output and blood volume) or peripheral factors is unknown. Purpose: To conduct a systematic review and meta-analysis to assess the effects of HIIT and SIT (referred to as intense interval training) on changes in central cardiovascular function. Methods: We performed a systematic search of eight databases for studies denoting increases in V̇O2max in which cardiac output (CO), stroke volume (SV), blood volume, plasma volume, end-diastolic/systolic volume, or hematocrit were measured. Results: Forty-five studies were included in this analysis, comprising 946 men and women of various health status (age and V̇O2max = 20 - 76 yr and 13 - 61 mL·kg-1·min-1) who performed 6 - 96 sessions of interval training. Results showed an increase in V̇O2max with intense interval training that was classified as a large effect (d = 0.83). Stroke volume (d = 0.69) and CO (d = 0.49) had moderate effect sizes in response to intense interval training. Of 27 studies in which CO was measured, 77 % exhibited significant increases in resting CO or that obtained during exercise. Similarly, 93 % of studies revealed significant increases in SV in response to intense interval training. Effect sizes for these outcomes were larger for clinical versus healthy populations. Plasma volume, blood volume, and hematocrit had small effect sizes after training (d = 0.06 - 0.14). Conclusions: Increases in V̇O2max demonstrated with intense interval training are attendant with increases in central O2 delivery with little contribution from changes in hematocrit, blood volume, or plasma volume.
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This study aims to develop an aerobic (oxidative steady-state) method of exercise based on an android application to improve the aerobic endurance of athletes, specifically in football. This application is designed according to the composition of aerobic endurance training. This application is beneficial in the current new normal situation, which requires players to practice independently. In addition, The application is expected to be a solution to the current situation—methods and steps in this study using the ADDIE model consist of 5 stages. The subjects in the study were two material experts, one media expert, and ten students who were learning about media users. The research was conducted at the Department of Sports Education, Riau University. The results of the development research tested in small groups were stated to be very feasible and suitable to be used as a guide to increase aerobic capacity. This application is still necessary to test in large groups in the use of this application to find out whether this learning media can be used by users widely
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چکیده هدف: تحقیق حاضر، بررسی تاثیر هشت هفته تمرین استقامتی در مقایسه با تمرین تناوبی با شدت بالا بر مقادیر A-VEGF و VEGFR2 در سه ناحیه استراتوم، هیپوکامپ و قشر بافت مغز موش صحرایی نر ویستار بود. روششناسی: بدین منظور از 24 سر موش نر نژاد ویستار (9 هفته،20±200 گرم) استفاده شد. موشها پس از یک هفته آشنایی با محیط آزمایشگاه به روش تصادفی به سه گروه: کنترل (Cont(؛ تمرین تداومی استقامتی؛ تمرین تناوبی با شدت بالا (HIIT (تقسیم و پروتکل هشت هفتهاي تمرین تداومی و تناوبی را انجام دادند. 24 ساعت پس از آخرین جلسه تمرین حیوانات کشته و نمونهگیري در سه ناحیه استراتوم، هیپوکامپ و قشر بافت مغز انجام گرفت. میزان پروتئین A-VEGF ،VEGFR2 از طریق روش وسترن بلات انجام شد. براي بررسی اختلاف معناداري در مقادیر A-VEGF و VEGFR2در سه گروه از آنالیز واریانس یکطرفه استفاده شد. یافتهها: نتایج نشان داد که مقادیر پروتئین A-VEGF در ناحیه استراتوم در گروه HIIT ،در ناحیه هیپوکامپ در گروه تمرین تداومی استقامتی و در ناحیه قشر هر در گروه HIIT بیش از گروه کنترل بود (5/0<P .(همچنین مقادیر پروتئین VEGFR2 در دو ناحیه استراتوم و هیپوکامپ در هر دو گروه بیش از گروه کنترل بود. در حالی که در ناحیه قشر این تفاوت معنیدار نبود. نتیجهگیري: یافتههاي پژوهش حاضر نشان داد که هر دو روش تمرین تداومی استقامتی و تناوبی با شدت بالا می تواند باعث افزایش مقادیر پروتئینهاي A-VEGF و VEGFR2 گردد . با این حال ورزش تناوبی با شدت بالا به علت مزیت زمانی میتواند جایگزینی مناسب براي تمرین تداومی استقامتی باشد. واژگان کلیدي: تمرین تناوبی با شدت بالا، A-VEGF ،2-VEGFR Effect of eight weeks continues and HIIT exercises on VEGF-A and VEGFR-2 levels in stratum, hippocampus and cortex of wistar rat brain Abstract The purpose of this study was to investigate the effect of eight week continues and HIIT exercise on VEGF-A and VEGFR-2 levels in stratum, hippocampus and cortex of wistar rat brain. Methods: for this purpose, 24 wistar rats (age: 9 weeks, weight: 200±20gr) were selected. After one week of familiarization with laboratory environment, they were randomly divided into three groups consisted of: control, continuous training and high intensity interval training. They did continuous and high-intensity interval training for eight-weeks. Twentyfour hours after last section of exercise they sacrificed and sampling of stratum, hippocampus and cortex were performed. Then, for assessment of VEGF-A and VEGFR-2 level, western blot method was used and for statistical analysis of the data's, the one-way ANOVA was used. Data of this study illustrated that VEGF-A protein in the stratum in HIIT and in hippocampus, the continuous training and in the cortex HIIT group was higher than the control group (P< 0/..5). Also VEGFR2 protein in the stratum and hippocampus area in both groups were higher than control group. While this difference was not significant in cortex. The results showed that both continuous and high-intensity interval training can increase the amount of VEGF-A and VEGFR2 proteins. Thus HIIT because of the time advantage can kye Words: be a substitute for continuous endurance training.
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Introduction High-intensity interval training (HIIT) may improve cardiorespiratory fitness (CRF) and mental health. The current observer-blinded RCT investigates the sparsely studied efficiency of HIIT in reducing psychotic and non-psychotic symptoms in schizophrenia and complements previous studies by investigating whether symptom reduction following HIIT is associated with, putatively partly mediated by, increased VO 2 max. Methods Participants (outpatients meeting diagnostic criteria for schizophrenia) were randomized to HIIT ( n = 43) or a comparison group performing low-intensity active video gaming (AVG) to control for social interaction ( n = 39). Both interventions consisted of two supervised sessions/week for 12 weeks and a months of follow-up. Effects on overall symptoms and symptom domains [PANSS (0–6 scale), five-factor model] were estimated using mixed-effects models (intention-to-treat, n = 82). Underlying mechanisms were analyzed using moderated mediation analyses ( n = 66). We anticipated that HIIT would reduce overall symptoms, particularly depressive symptoms, more than AVG, and symptom reduction would be associated with, putatively mediated through, improved VO 2 max. Results Depressive symptoms (baseline score 3.97, 95% CI: 3.41, 4.52), were −1.03 points more reduced in HIIT than AVG at post-intervention (95% CI: −1.71, −0.35, p = 0.003), corresponding to a small to moderate effect size ( d = 0.37) and persisting at follow-up. There was a small reduction in overall symptoms, but no significant between-group differences were observed. Change in VO 2 max correlated negatively with the change in depressive symptoms. Mediation analysis showed a significant effect of change in VO 2 max on change in depressive symptoms within HIIT. The total effect was moderated by group, and depressive symptoms were more reduced in HIIT. Direct effects, not mediated through VO 2 max, were non-significant. Indirect effects, mediated through VO 2 max, were non-significant, but the moderated mediation test indicated a non-significant trend of 0.4 points (95% CI: −1.188, 0.087) and a larger reduction in depressive symptoms through VO 2 max in HIIT. Conclusion HIIT reduced depressive symptoms more than AVG, which persisted at follow-up. HIIT may serve as a complementing treatment option targeting these symptoms in individuals with schizophrenia, even before they reach clinical depression. Depressive symptoms are important to prevent, stabilize, and treat due to their negative implications for psychological wellbeing and long-term functional outcome. Reduction in depressive symptoms was associated with improved VO 2 max, and non-significant trends in the data supported that improved VO 2 max may be part of the complex mechanisms underlying the anti-depressive effect of HIIT. Clinical Trial Registration [ www.ClinicalTrials.gov ], identifier [NCT02205684].
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Stroke volume (SV) responses during graded treadmill exercise were studied in 1) elite male distance runners (N = 5), 2) male university distance runners (N = 10), and 3) male untrained university students (N = 10). Cardiac output (Q) and SV were determined by a modified acetylene rebreathing procedure. There were no differences in SV responses among the three groups during the transition from rest to light exercise (P > 0.05). However, the rates of change of SV during light to maximal exercise in untrained subjects (slope = -0.1544 mL x beat(-1)) and university distance runners (slope = 0.1041) did not change, whereas it dramatically increased (P < 0.001) in elite distant runners (slope = 0.6734). Moreover, the elite distance runners showed a further slope increase in SV when heart rate was above 160 bpm, which resulted in an average maximal SV of 187 +/- 14 mL x beat(-1) compared with 145 +/- 8 and 128 +/- 14 mL x beat(-1) in the university runners and untrained students, respectively (P < 0.001). Similarly, max Q reached 33.8 +/- 2.3, 26.3 +/- 1.7, and 21.3 +/- 1.5 L x min(-1) in the three groups, respectively (P < 0.001). On the other hand, there was a nonsignificant tendency for maximal arteriovenous oxygen content difference to be lower in the elite athletes compared with the other groups. Results from university distance runners and untrained university students support the classic observation that SV plateaus at about 40% of maximal oxygen consumption despite increasing intensity of exercise. In contrast, stroke volume in the elite athletes does not plateau but increases continuously with increasing intensity of exercise over the full range of the incremental exercise test.
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The effects of low intensity endurance training on skeletal muscle capillary density and serum lipoprotein levels were studied in 11 non-obese men (18-25 years). The subjects performed a 6-week training regimen (60 min, 5 times per week) at the lactate threshold (LT). Capillary density was determined in biopsy specimens obtained from the vastus lateralis muscle before and after the training. The number of capillaries per fiber (cap/fiber ratio) before training was 1.97 +/- 0.47, and increased to 2.49 +/- 0.69 after training (p < 0.05). The maximal oxygen uptake (VO2 max) and LT- VO2 increased significantly by 5% (p < 0.01) and 27% (p < 0.01), respectively, whereas no change was observed in body weight. Low density lipoprotein cholesterol (LDL-C) tended to decrease (p = 0.06). The change in the cap/fiber ratio correlated inversely with the change in the ratio of LDL-C to high density lipoprotein cholesterol (HDL-C) (r = -0.61, p < 0.05). It was also, positively associated with the change in HDL2-C (r = 0.82, p < 0.01) and inversely associated with the change in HDL3-C (r = -0.63, p < 0.05). The change in LT- VO2 was inversely associated with the change in LDL-C (r = -0.62, r < 0.05). These results indicate that low intensity training increases capillary density in skeletal muscle, which may explain in part the changes in the lipoprotein profiles.
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Thesis (Ph.D.) -- Brigham Young University. Dept. of Physical Educational, 1999. Includes bibliographical references. cat
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Maximal aerobic power of 37 athletes (14 females and ten male cross-country skiers, eight male rowers and five male cyclists) was determined during uphill running on the treadmill and during maximal performance of their specific sport activity. For the skiers a significantly (P less than 0.005) higher VO2max was found during uphill skiing than during running, the differences being 2.9 and 3.1% for the females and males, respectively. The rowers and cyclists obtained a difference of 4.2 and 5.6%, respectively (P less than 0.01). The largest individual differences between the two test procedures were 12.2, 5.4, 14.3, and 7.9% for female and male cross-country skiers, rowers, and cyclists, respectively. It is concluded that in evaluation of maximal aerobic power of atheletes, it becomes important to select a work situation which allows optimal use of the specifically trained muscle fibres. This means that the test preferably should be identical with the subjects' specific sport activity, under the assumption that a reasonably large muscle mass is engaged during the performance.
Six male and six female runners were chosen on the basis of age (20-30 years) and their performance over the marathon distance (mean time = 199.4, SEM 2.3 min for men and 201.8, SEM 1.8 min for women). The purpose was to find possible sex differences in maximal aerobic power (VO2max), anaerobic threshold, running economy, degree and utilization of VO2max (when running a marathon) and amount of training. The results showed that performance-matched male and female marathon runners had approximately the same VO2max (about 60 ml.kg-1.min-1). For both sexes the anaerobic threshold was reached at an exercise intensity of about 83% of VO2max, or 88%-90% of maximal heart rate. The females' running economy was poorer, i.e. their oxygen uptake during running at a standard submaximal speed was higher (P less than 0.05). The heart rate, respiratory exchange ratio and blood lactate concentration also confirmed that a given running speed resulted in higher physiological strain for the females. The percentage utilization of VO2max at the average marathon running speed was somewhat higher for the females, but the difference was not significant. For both sexes the oxygen uptake at average speed was 93%-94% of the oxygen uptake corresponding to the anaerobic threshold. Answers to a questionnaire showed that the females' training programme over the last 2 months prior to running the actual marathon comprised almost twice as many kilometers of running per week compared to the males (60 and 33 km, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
The energy demand of running on a treadmill was studied in different groups of trained athletes of both sexes. We have not found any significant differences in the net energy cost (C) during running (expressed in J.kg-1.m-1) between similarly trained groups of men and women. For men and women respectively in adult middle distance runners C = 3.57 +/- 0.15 and 3.65 +/- 0.20, in adult long-distance runners C = 3.63 +/- 0.18 and 3.70 +/- 0.21, in adult canoeists C = 3.82 +/- 0.34 and 3.80 +/- 0.24, in young middle-distance runners C = 3.84 +/- 0.18 and 3.78 +/- 0.26 and in young long-distance runners C = 3.85 +/- 0.12 and 3.80 +/- 0.24. This similarity may be explained by the similar training states of both sexes, resulting from the intense training which did not differ in its relative intensity and frequency between the groups of men and women. A negative relationship was found between the energy cost of running and maximal oxygen uptake (VO2max) expressed relative to body weight (for men r = -0.471, p less than 0.001; for women r = -0.589, p less than 0.001). In contrast, no significant relationship was found in either sex between the energy cost of running and VO2max. We conclude therefore that differences in sports performance between similarly trained men and women are related to differences in VO2max.kg-1. The evaluation of C as an additional characteristic during laboratory tests may help us to ascertain, along with other parameters, not only the effectiveness of the training procedure, but also to evaluate the technique performed.
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This review has grouped many studies on different populations with different protocols to show the interactive effects of intensity, frequency and duration of training as well as the effects of initial fitness levels and programme length on cardiorespiratory fitness as reflected by aerobic power (V̇O2max). Within each level of exercise duration, frequency, programme length or initial fitness level, the greatest improvements in aerobic power occur when the greatest challenge to aerobic power occurs i.e., when intensity is from 90 to 100% of V̇O2max. The pattern of improvement where different intensities are compared with different durations suggests that when exercise exceeds 35 minutes, a lower intensity of training results in the same effect as those achieved at higher intensities for shorter durations. Frequencies of as low as 2 per week can result in improvements in less fit subjects but when aerobic power exceeds 50 ml/kg/min, exercise frequency of at least 3 times per week is required. As the levels of initial fitness improve, the change in aerobic power decreases regardless of the intensity, frequency or duration of exercise. Although these pooled data suggest that maximal gains in aerobic power are elicited with intensities between 90 to 100% V̇O2 max, 4 times per week with exercise durations of 35 to 45 minutes, it is important to note that lower intensities still produce effective changes and reduce the risks of injury in non-athletic groups.
Maximal O2 consumption ($$\dot V_{O_{_2 max} }$$ and energy cost of running per unit distance (C) were determined on the treadmill in 36 male amateur runners (17 to 52 years) who had taken part in a marathon (42.195 km) or semi-marathon (21 km), their performance times varying from 149 to 226 and from 84 to 131 min, respectively.$$\dot V_{O_{_2 max} }$$ was significantly (2p<0.001) greater in the marathon runners (60.6 vs 52.1 ml · kg−1 · min−1) whileC was the same in both groups (0.179±0.017, S.D., mlO2 · kg−1 · m−1 above resting), and independent of treadmill speed. It can be shown that the maximal theoretical speed in endurance running (vEND) is set by$$\dot V_{O_{_2 max} }$$, its maximal sustainable fraction (F), andC, as described by:vEND=F ·$$\dot V_{O_{_2 max} }$$ ·C −1. SinceF was estimated from the individual time of performance,vEND could be calculated. The average speed of performance (vMIG) andvEND (m · s−1) were found to be linearly correlated:vMIG=1.12+0.64vEND (r 2=0.72;n=36). The variability ofvMIG explained byvEND, as measured byr 2, is greater than that calculated from any one regression betweenvMIG and$$\dot V_{O_{_2 max} }$$ (r 2=0.51),F ·$$\dot V_{O_{_2 max} }$$ (r 2=0.58), or$$\dot V_{O_{_2 max} }$$ ·C −1 (r 2=0.63). The mean ratio of observed (vMIG) to theoretical (vEND) speeds amounted to 0.947±0.076 and increased to 0.978±0.079 (±S.D.;n=36) when the effects of air resistance were taken into account. It is concluded thatvEND=F ·$$\dot V_{O_{_2 max} }$$ ·C −1 is a satisfactory quantitative description of the energetics of endurance running.
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To characterize the hemodynamic factors that regulate stroke volume during upright exercise in normal man, 24 asymptomatic male volunteers were evaluated by simultaneous right heart catheterization, radionuclide angiography, and expired gas analysis during staged upright bicycle exercise to exhaustion. From rest to peak exercise, oxygen consumption increased from 0.33 to 2.55 liters/min (7.7-fold), cardiac index increased from 3.0 to 9.7 liters/min per m2 (3.2-fold), and arteriovenous oxygen difference increased from 5.8 to 14.1 vol% (2.5-fold). The increase in cardiac index resulted from an increase in heart rate from 73 to 167 beats/min (2.5-fold), and an increase in left ventricular stroke volume index from 41 to 58 ml/m2 (1.4-fold). During low levels of exercise, there was a linear increase in cardiac index due to an increase in both heart rate and stroke volume index; stroke volume index increased as a result of an increase in left ventricular filling pressure and end-diastolic volume index and, to a much smaller extent, a decrease in end-systolic volume index. During high levels of exercise, further increases in cardiac index resulted entirely from an increase in heart rate, since stroke volume index increased no further. Left ventricular end-diastolic volume index decreased despite a linear increase in pulmonary artery wedge pressure; stroke volume index was maintained by a further decrease in end-systolic volume index. The degree to which stroke volume index increased during exercise in individuals correlated with the change in end-diastolic volume index (r = 0.66) but not with the change in end-systolic volume index (r = 0.07). Thus, the mechanism by which left ventricular stroke volume increases during upright exercise in man is dependent upon the changing relationship between heart rate, left ventricular filling, and left ventricular contractility. At low levels of exertion, an increase in left ventricular filling pressure and end-diastolic volume are important determinants of the stroke volume response through the Starling mechanism. At high levels of exertion, the exercise tachycardia is accompanied by a decrease in end-diastolic volume despite a progressive increase in filling pressure, so that stroke volume must be maintained by a decrease in end-systolic volume.
Article
Swedish military conscripts participated in 3 separate programs of interval training (principal activity - running): Group I (N = 20): 15 sec exercise + 15 sec rest, 3 days/week for 2 months. Group II (N = 9): 3 min exercise + 3 min rest, 3 days/week for 2 months, Group III (N = 8): 1 month no formal program, then 3 min exercise + 3 min rest, 5 days/week for 1 month. For each group, total time for exercise of high intensity = 15 min per session. Testing was performed on a cycle ergometer at induction, after 1 month, and after 2 months. Significant increases in max[latin capital V with dot above]o2 were observed for all groups (mean increase approximately 20%). Maximal oxygen uptake increased from 3.1, 2.9 and 3.2 to 3.6, 3.6 and 3.9 ] x min-1 for groups I, II and III, respectively. Concomitant reductions occurred in HR and perceived exertion at submaximal exercise (150 W). Individual improvement was inversely related to initial fitness, the lower the level at induction the greater the increase relative to this value. Subgroups tested 8 months after cessation of training (at discharge) had regressed to levels not different from those at induction. Conclusions: 1) physical fitness in this age group can be markedly and rapidly improved by interval training, 2) marked improvement in aerobic power capacity can be brought about by an impressively short time investment, 3) the training regimen based on 3-min periods was more effective than 15-sec periods, and 4) military life in this situation (communications regiment) was not sufficient to maintain a high level of fitness when the physical conditioning program was discontinued. (C)1973The American College of Sports Medicine
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Viable articular cartilage from the medial femoral condyles of rabbits was stored in vitro in tissue culture medium with various additives and the same site of each specimen was mechanically tested sequentially throughout a 12-day storage period. Indentation testing was performed with instantaneous and sustained loads. Preservation of sustained-load carrying capacity was observed in the condyles stored with additives, indicating maintenance of an intact cartilage matrix. However, initial testing with small sustained loads (preload) showed changes not observed at higher load levels. The changes noted at small sustained initial loads may reflect alterations in cartilage surface structure and may be an early indicator of its mechanical integrity. Chondrocyte viability and proteoglycan content, as measured by 35S incorporation and hexosamine concentration, were unchanged in comparison to fresh articular cartilage.
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This study attempted to determine the effects of interval and continuous running on factors associated with cardiovascular health. Fifty-nine untrained men and women, ages 18-32 years, were randomly assigned to one of four groups: (1) 4 mile: running continuously at 75% of maximal heart rate (approximately 500 Cal/session) (2) 2 mile: running continuously at 75% of maximal heart rate (approximately 250 Cal/session) (3) interval: running one min at 90% maximal heart rate followed by three min of walking for eight sets (approximately 500 Cal/session) (4) control: no exercise program. The training was performed three times per week for 12 weeks. Treadmill VO2 max and percent body fat by hydrostatic weighing were assessed pre- and post training. Pre and post analyses were performed on plasma for triglycerides (TG), cholesterol (Chol), and high density lipoprotein cholesterol (HDL-C). Analysis of covariance indicated that only the interval group improved more than the control in VO2 max. Percent fat decreased in all exercise groups, but no program was superior. Changes in TG, Chol, or HDL-C were not different among groups. Although men and women differed on the pretests in VO2 max, percent fat, and HDL-C, their response to the training was similar. These results indicate that interval training may benefit aerobic capacity more than continuous running in young adults who have moderately high initial fitness levels. The data also indicate that cardiovascular fitness parameters are not easily altered by short term exercise in young active men and women.
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The American College of Sports Medicine (ACSM) recommends the use of 40%, 60%, 80%, and 85% of maximal oxygen consumption (VO2max) as target values in developing exercise prescriptions. Further, the ACSM states that 55%, 70%, 85%, and 90% of maximal heart rate (HRmax) may be used as indices of these respective levels of % VO2max for the general population. The current study evaluated this relationship between %HRmax and %VO2max in apparently healthy, young adults. Eighty-one men and 81 women between the ages of 18 and 34 engaged in an incremental exercise test to exhaustion. Linear regressions of %HRmax and %VO2max were performed on each subject. From these regressions, target values of %HRmax were computed for each individual. Mean percentages of HRmax were 63%, 76%, 89%, and 92% at 40%, 60%, 80%, and 85% of VO2max, respectively. At all of these values of %VO2max, the values obtained for %HRmax were significantly greater (P < 0.001) than those used by the ACSM. Fitness affected these results, particularly among men. High fit men averaged 2% higher in %HRmax than low fit men at any given value of %VO2max.
Sex differences in running economy (gross oxygen cost of running, CR), maximal oxygen uptake (VO2max), anaerobic threshold (Than), percentage utilization of aerobic power (% VO2max), and Than during running were investigated. There were six men and six women aged 20–30 years with a performance time of 2 h 40 min over the marathon distance. The VO2max, Than, and CR were measured during controlled running on a treadmill at 1° and 3° gradient. From each subject's recorded time of running in the marathon, the average speed (v M) was calculated and maintained during the treadmill running for 11 min. The VO2 max was inversely related to body mass (m b), there were no sex differences, and the mean values of the reduced exponent were 0.65 for women and 0.81 for men. These results indicate that for running the unit ml·kg−0.75·min−1 is convenient when comparing individuals with different m b. The VO2max was about 10% (23 ml·kg−0.75·min−1) higher in the men than in the women. The women had on the average 10–12 ml·kg−0.75·min−1 lower VO2 than the men when running at comparable velocities. Disregarding sex, the mean value of CR was 0.211 (SEM 0.005) ml·kg−1·m−1 (resting included), and was independent of treadmill speed. No sex differences in Than expressed as % VO2max or percentage maximal heart rate were found, but Than expressed as VO2 in ml·kg−0.75·min−1 was significantly higher in the men compared to the women. The percentage utilization of f emax and concentration of blood lactate at v M was higher for the female runners. The women ran 2 days more each week than the men over the first 4 months during the half year preceding the marathon race. It was concluded that the higher VO2max and Than in the men was compensated for by more running, superior CR, and a higher exercise intensity during the race in the performance-matched female marathon runners.
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When maximal VO2 (VO2 MAX) is limited by O2 supply, it is generally thought that cardiac output (QT) is mostly responsible, but other O2 transport conductances [ventilation (VA); [Hb]; pulmonary (DLO2) and muscle (DMO2) diffusion capacities] may also influence VO2 MAX. A numerical analysis interactively linking the lungs, circulation and muscles was designed to compare the influences of each conductance component on VO2 MAX at three altitudes: PB = 760, 464 and 253 Torr. For any given set of conductances the analysis simultaneously solved six equations for alveolar, arterial, and venous PO2 and PcO2. The equations represent pulmonary mass balance, pulmonary diffusion, and muscle diffusion for both gases. At PB = 760, [Hb], DLO2 and DMO2 were as influential as QT in limiting VO2 MAX. With increasing altitude, the influence of QT and [Hb] fell while that of VA, DLO2 and DMO2 progressively increased until at PB = 253, VO2 MAX was independent of QT and [Hb]. Neither the fall in maximal QT nor rise in [Hb] with chronic hypoxia therefore appear to affect VO2 MAX. However, high values of ventilation, DLO2 and DMO2 appear to be advantageous for exercise at altitude.
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To compare the effects of three types of intensive run training on running economy (RE) during exhaustive running and to establish possible relationships with changes in ventilatory function and/or muscle fiber type distribution. Thirty-six male recreational runners were divided into three groups and assigned to either exhaustive distance training (DT), long-interval training (LIT), or short-interval training (SIT) three times 20-30 minxwk(-1) for 6 wk. VO(2 max) and RE were measured during treadmill running before and after training. Muscle fiber type distribution of the vastus lateralis muscle was established from biopsy material. VO(2max) (Lxmin(-1) increased by 5.9% (P < 0.0001), 6.0% (P < 0.0001), and 3.6% (P < 0.01) in DT, LIT, and SIT, respectively, and running speed at VO(2max) by 9% (P < 0.0001), 10% (P < 0.0001), and 4% (P < 0.05), respectively. Time-to-exhaustion at 87% of pretraining VO(2max) (mean 3.83) mxs(-1) increased by 94% in DT (P < 0.0001), 67% in LIT (P < 0.0001). Running economy improved by 3.1% in DT (P < 0.05), 3.0% in LIT (P < 0.01), and 0.9% SIT (NS): pulmonary ventilation (VE) was on average 11 Lxmin(-1) lower following training (P < 0.0001). The individual decrements in VE correlated with improvements in RE (r = 0.77; P < 0.0001) and may account for 25-70% of the decrease in aerobic demand. Muscle fiber composition, and respiratory exchange ratio, stride length, and stride frequency during running were unaltered with training. Recreational runners can improve RE and aerobic run performance by exchanging parts of their conventional aerobic distance training with intensive distance or long-interval running, whereas short-interval running is less efficient. The improvement in RE may relate to reduced ventilatory demands. Muscle fiber type distribution was unaltered with training and showed no associations with RE.
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The training intensity may affect the monocarboxylate transporters MCT1 and MCT4 in skeletal muscle. Therefore, 20 elite cross-country skiers (11 men and nine women) trained hard for 5 months at either moderate (MIG, 60-70% of VO2max) or high intensity (HIG, 80-90%). The lactate threshold, several performance parameters, and the blood lactate concentration (cLa) after exhausting treadmill running were also determined. Muscle biopsies taken from the vastus lateralis muscle before and after the training period were analysed for the two MCTs and for muscle fibre types and six enzymes. The concentration of MCT1 did not change for HIG (P=0.3) but fell for MIG (-12 +/- 3%, P=0.01); the training response differed between the two groups (P=0.05). The concentration of MCT4 did not change during the training period (P > 0.10). The concentration of the two MCTs did not differ between the two sexes (P=0.9). The running speed at the lactate threshold rose for HIG (+3.2 +/- 0.9%, P=0.003), while no change was seen for MIG (P=0.54); the training response differed between the two groups (P=0.04). The cLa after long-lasting exhausting treadmill running correlated with the concentration of MCT1 (rs=0.69, P=0.002), but not with that of MCT4 (rs=0.2, P=0.2). There were no other significant correlations between the concentrations of the two MCTs and the performance parameters, muscle fibre types, or enzymes (r < or = 0.36, P > 0.10). Thus, the training response differed between MIG and HIG both in terms of performance and of the effect on MCT1. Training at high intensity may be more effective for cross-country skiers. Finally, MCT1 may be important for releasing lactate to the blood during long-lasting exercise.
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The aim of the present study was to study the effects of aerobic training on performance during soccer match and soccer specific tests. Nineteen male elite junior soccer players, age 18.1 +/- 0.8 yr, randomly assigned to the training group (N = 9) and the control group (N = 10) participated in the study. The specific aerobic training consisted of interval training, four times 4 min at 90-95% of maximal heart rate, with a 3-min jog in between, twice per week for 8 wk. Players were monitored by video during two matches, one before and one after training. In the training group: a) maximal oxygen uptake (VO2max) increased from 58.1 +/- 4.5 mL x kg(-1) x min(-1) to 64.3 +/- 3.9 mL x kg(-1) x min(-1) (P < 0.01); b) lactate threshold improved from 47.8 +/- 5.3 mL x kg(-1) x min(-1) to 55.4 +/- 4.1 mL x kg(-1) x min(-1) (P < 0.01); c) running economy was also improved by 6.7% (P < 0.05); d) distance covered during a match increased by 20% in the training group (P < 0.01); e) number of sprints increased by 100% (P < 0.01); f) number of involvements with the ball increased by 24% (P < 0.05); g) the average work intensity during a soccer match, measured as percent of maximal heart rate, was enhanced from 82.7 +/- 3.4% to 85.6 +/- 3.1% (P < 0.05); and h) no changes were found in maximal vertical jumping height, strength, speed, kicking velocity, kicking precision, or quality of passes after the training period. The control group showed no changes in any of the tested parameters. Enhanced aerobic endurance in soccer players improved soccer performance by increasing the distance covered, enhancing work intensity, and increasing the number of sprints and involvements with the ball during a match.
Article
The aim of this experiment was to examine the effects of maximal strength training with emphasis on neural adaptations on strength- and endurance-performance for endurance trained athletes. Nineteen male cross-country skiers about 19.7 +/- 4.0 years of age and a maximal oxygen uptake (VO(2 max)) of 69.4 +/- 2.2 mL x kg(-1) x min(-1) were randomly assigned to a training group (n = 9) or a control group (n = 10). Strength training was performed, three times a week for 8 weeks, using a cable pulley simulating the movements in double poling in cross-country skiing, and consisted of three sets of six repetitions at a workload of 85% of one repetition maximum emphasizing maximal mobilization of force in the concentric movement. One repetition maximum improved significantly from 40.3 +/- 4.5 to 44.3 +/- 4.9 kg. Time to peak force (TPF) was reduced by 50 and 60% on two different submaximal workloads. Endurance performance measured as time to exhaustion (TTE) on a double poling ski ergometer at maximum aerobic velocity, improved from 6.49 to 10.18 min; 20.5% over the control group. Work economy changed significantly from 1.02 +/- 0.14 to 0.74 +/- 0.10 mL x kg(-0.67) x min(-1). Maximal strength training with emphasis on neural adaptations improves strength, particularly rate of force development, and improves aerobic endurance performance by improved work economy.
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Increased aerobic exercise capacity appears to reduce both all-cause mortality and cardiovascular disease mortality. Physical exercise to improve peak oxygen uptake (VO2peak) is thus strongly recommended, however evidence regarding the most efficient training intensity for patients with coronary artery disease (CAD) is still lacking. The purpose of this randomized study was therefore to assess the effects of high intensity aerobic interval exercise compared to moderate intensity exercise, representing the same total training load, for increasing VO2peak in stable CAD-patients. Twenty-one stable CAD-patients were randomized to supervised treadmill walking at either high intensity (80-90% of VO2peak) or moderate intensity (50-60% of VO2peak) three times a week for 10 weeks. After training VO2peak increased by 17.9% (P=0.012) in the high intensity group and 7.9% (P=0.038) in the moderate intensity group. The training-induced adaptation was significantly higher in the high intensity group (P=0.011). High intensity aerobic interval exercise is superior to moderate exercise for increasing VO2peak in stable CAD-patients. As VO2peak seems to reflect a continuum between health and cardiovascular disease and death, the present data may be useful in designing effective training programmes for improved health in the future.