Low Training Intensity Research Articles

Effects of short bout small-sided game training on acid-base balance markers in youth male soccer players

This study aimed to compare the effects of 1 × 1 small-sided games (SSGs) with different bout durations on external (ETL) and internal training loads (ITL) in youth soccer players. Twenty U18 players were divided into two groups performing six 1 × 1 SSGs with 30 and 45 s bout durations on a playing field of 10 by 15 m. ITL indices, including the percentage of maximum heart rate (HR), blood lactate (BLa) level, pH, bicarbonate (HCO3−) level, and base excess (BE) level, were measured at rest, after each SSG bout, and 15 and 30 min after the entire exercise protocol. ETL (Global Positioning System metrics) was recorded during all six SSG bouts. The analysis showed that the 45 s SSGs had a greater volume (large effect) but a lower training intensity (small to large effect) than the 30 s SSGs. A significant time effect (p < 0.05) was observed in all ITL indices and a significant group effect (F1, 18 = 8.84, p = 0.0082, ƞ2 = 0.33) in the HCO3− level only. Finally, the changes in the HR and HCO3− level were smaller in the 45 s SSGs than in the 30 s SSGs. In conclusion, 30-s games, characterized by a higher intensity of training effort, are more physiologically demanding than 45-s games. Secondly during short-bout SSG training the HR and BLa level have limited diagnostic value for ITL. Extending ITL monitoring using other indicators, such as the HCO3− and BE levels, appears reasonable.

Outdoor walking better? environmental elements of cardiorespiratory fitness training trails.

In metropolitan areas where land resources are scarce, trails are a more suitable environment for cardiorespiratory fitness training for modern people. Previous studies have demonstrated that cardiorespiratory fitness is an important factor in assessing individual health and have focused on individual training performance, but the relationship between environment and cardiorespiratory fitness training participants has rarely been investigated. The purpose of this study was to investigate the demands for outdoor cardiorespiratory fitness training and a favorable trail environment by comparing the differences in exercise intensity and perceptions between outdoor and indoor environments. In this study, information on physical data, psychological feedback, and visual atmosphere was collected from nine participants during each phase of moderate intensity cardiorespiratory fitness training in indoor and outdoor environments. The results revealed that outdoor cardiorespiratory fitness training provided participants with lower training intensity during the active exercise phase and higher heart rate during the stretching phase compared to indoor training. The participants paid more attention to the slope, length, pavement, Spaciousness, and width of the trails and the circuitous route. The change of the visual atmosphere and the scenery for the environmental factors were the important factors to motivate the participants to train. The results of the study could assist participants to understand a favorable cardiorespiratory training environment and design a suitable training program, as well as provide a model for trail planning and design for government.

Training load, sports performance, physical and mental health during the COVID-19 pandemic: A prospective cohort of Swiss elite athletes.

The COVID-19 pandemic and associated restrictions have led to abrupt changes in the lives of elite athletes. The objective of this prospective cohort study was to examine training load, subjective sports performance, physical and mental health among Swiss elite athletes during a 6-month follow-up period starting with the first Swiss lockdown. Swiss elite athletes (n = 203) participated in a repeated online survey evaluating health, training, and performance related metrics. After the first assessment during the first lockdown between April and May 2020, there were monthly follow-ups over 6 months. Out of 203 athletes completing the first survey during the first lockdown, 73 athletes (36%) completed all assessments during the entire 6-month follow-up period. Sports performance and training load decreased during the first lockdown and increased again at the beginning of the second lockdown in October 2020, while symptoms of depression and financial fears showed only a transient increase during the first lockdown. Self-reported injuries and illnesses did not change significantly at any timepoint in the study. Stricter COVID-19 restrictions, as measured by the Government Stringency Index (GSI), were associated with reduced subjective sports performance, as well as lower training intensity, increased financial fears, poorer coping with restrictions, and more depressive symptoms, as measured by the 9-item module of the Patient Health Questionnaire-9 (PHQ-9). This study revealed a negative impact of the COVID-19 restrictions on sports performance, training load and mental health among Swiss elite athletes, while the rate of self-reported injuries and illnesses remained unaffected.

Skeletal Muscle Satellite Cells in Sickle Cell Disease Patients and Their Responses to a Moderate-intensity Endurance Exercise Training Program.

We previously demonstrated that 8 weeks of moderate-intensity endurance training is safe and improves muscle function and characteristics of sickle cell disease (SCD) patients. Here, we investigated skeletal muscle satellite cells (SCs) in SCD patients and their responses to a training program. Fifteen patients followed the training program while 18 control patients maintained a normal lifestyle. Biopsies of the vastus lateralis muscle were performed before and after training. After training, the cross-sectional area and myonuclear content in type I fibers were slightly increased in the training patients compared to non-training patients. The SC pool was unchanged in type I fibers while it was slightly decreased in type II fibers in the training patients compared to non-training patients. No necrotic fibers were detected in patients before or after training. Therefore, the slight myonuclear accretion in type I fibers in trained SCD patients may highlight the contribution of SCs to training-induced slight type I fiber hypertrophy without expansion of the SC pool. The low training intensity and the short duration of training sessions could explain the low SC response to the training program. However, the lack of necrotic fibers suggests that the training program seemed to be safe for patients' muscle tissue.

Prevalence and Risk Factors of Psychiatric Symptoms among Swiss Elite Athletes during the First Lockdown of the COVID-19 Pandemic.

The COVID-19 pandemic and the associated first lockdown measures may have had a relevant impact on the mental health of competitive athletes. This study aimed to evaluate the prevalence of various mental health issues in a Swiss elite athletes’ cohort during the first lockdown of the pandemic, and to assess their association with different potential risk factors. Elite athletes from different disciplines were interviewed during the first lockdown in spring 2020 by means of an online questionnaire on symptoms of existing anxieties, depression and sleep disorders, as well as on training circumstances and physical performance before and during the lockdown. Additionally, the economic situation, secondary occupations and current physical health problems were surveyed. A total of 203 (92 female, 111 male) athletes met the inclusion criteria and participated in the survey. Training volume and intensity decreased significantly during lockdown from 3.1 to 2.7 h/day. Financial existential fears increased and were associated with higher training volumes and higher trait anxiety scores. Depressive symptoms and insomnia were present but not exceptionally frequent during the lockdown. Depressive symptoms were associated with higher anxiety scores, higher insomnia severity scores, lower training intensity and worse coping with the measures taken by the authorities against the pandemic. Changes in training and daily habits due to the first lockdown may have affected the mental health of elite athletes. Longitudinal studies should, however, further investigate the long-term effects of the pandemic on mental health.

Development of an EMG-Controlled Knee Exoskeleton to Assist Home Rehabilitation in a Game Context.

As a leading cause of loss of functional movement, stroke often makes it difficult for patients to walk. Interventions to aid motor recovery in stroke patients should be carried out as a matter of urgency. However, muscle activity in the knee is usually too weak to generate overt movements, which poses a challenge for early post-stroke rehabilitation training. Although electromyography (EMG)-controlled exoskeletons have the potential to solve this problem, most existing robotic devices in rehabilitation centers are expensive, technologically complex, and allow only low training intensity. To address these problems, we have developed an EMG-controlled knee exoskeleton for use at home to assist stroke patients in their rehabilitation. EMG signals of the subject are acquired by an easy-to-don EMG sensor and then processed by a Kalman filter to control the exoskeleton autonomously. A newly-designed game is introduced to improve rehabilitation by encouraging patients' involvement in the training process. Six healthy subjects took part in an initial test of this new training tool. The test showed that subjects could use their EMG signals to control the exoskeleton to assist them in playing the game. Subjects found the rehabilitation process interesting, and they improved their control performance through 20-block training, with game scores increasing from 41.3 ± 15.19 to 78.5 ± 25.2. The setup process was simplified compared to traditional studies and took only 72 s according to test on one healthy subject. The time lag of EMG signal processing, which is an important aspect for real-time control, was significantly reduced to about 64 ms by employing a Kalman filter, while the delay caused by the exoskeleton was about 110 ms. This easy-to-use rehabilitation tool has a greatly simplified training process and allows patients to undergo rehabilitation in a home environment without the need for a therapist to be present. It has the potential to improve the intensity of rehabilitation and the outcomes for stroke patients in the initial phase of rehabilitation.

How does a 4-week motor-cognitive training affect choice reaction, dynamic balance and cognitive performance ability? A randomized controlled trial in well-trained, young, healthy participants.

Background:We aimed to investigate the potential effects of a 4-week motor–cognitive dual-task training on cognitive and motor function as well as exercise motivation in young, healthy, and active adults.Methods:A total of 26 participants (age 25 ± 2 years; 10 women) were randomly allocated to either the intervention group or a control group. The intervention group performed a motor–cognitive training (3×/week), while the participants of the control group received no intervention. Before and after the intervention period of 4 weeks, all participants underwent cognitive (d2-test, Trail Making Test) and motor (lower-body choice reaction test and time to stabilization test) assessments. Following each of the 12 workouts, self-reported assessments (rating of perceived exertion, enjoyment and pleasant anticipation of the next training session) were done. Analyses of covariances and 95% confidence intervals plotting for between group and time effects were performed.Results:Data from 24 participants were analysed. No pre- to post-intervention improvement nor a between-group difference regarding motor outcomes (choice-reaction: F = 0.5; time to stabilization test: F = 0.7; p > 0.05) occurred. No significant training-induced changes were found in the cognitive tests (D2: F = 0.02; Trail Making Test A: F = 0.24; Trail Making Test B: F = 0.002; p > 0.05). Both enjoyment and anticipation of the next workout were rated as high.Discussion:The neuro-motor training appears to have no significant effects on motor and cognitive function in healthy, young and physically active adults. This might be explained in part by the participants’ very high motor and cognitive abilities, the comparably low training intensity or the programme duration. The high degree of exercise enjoyment, however, may qualify the training as a facilitator to initiate and maintain regular physical activity. The moderate to vigorous intensity levels further point towards potential health-enhancing cardiorespiratory effects.

A car-face region-based image retrieval method with attention of SIFT features

A traffic still image captured by the high-definition camera located in traffic block port often contains several vehicles. It provides an important clue to solve vehicle crime cases to retrieve all these images that contain the given type of car. To enhance the performance of image retrieval, we proposed a car-face region-based image retrieval method with the attention of SIFT features. In our method, the first step is to find all the car-face regions from an original traffic image, and this original image is represented as a set of car-face regions. Secondly, a similarity measure metrics is proposed with a light intense training of the attention value of SIFT key points on a very small identified images set. Finally, according to the similarity between the input region and the target region, all the images with at least one similar region are retrieved. We carry out this method on a training set of 100 positive car-face region-images. Compared with the famous training-based SVM method, our method achieved higher precision at the same recall with lower training intensity.

Inspiratory muscle training protocol for patients with chronic obstructive pulmonary disease (IMTCO study): a multicentre randomised controlled trial

IntroductionInspiratory muscle training (IMT) has been applied during pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD). However, it remains unclear if the addition of IMT to a general...

The influence of a six month aerobics programme on middle aged women's aerobic capacity and body composition

Background: Regular physical activity has a positive influence on increasing physical fitness, which has considerable impact on health and, consequently, on the quality and length of human life. Objective: The aim of the study was to assess the influence of six months of physical endurance activity on the body composition and aerobic capacity of middle aged women. Methods: Forty women between the ages of 40 to 55 years with a sedentary occupation and without regular physical activity took part in the study. The experimental group (n = 21) participated in dance aerobics lessons combined with strength training three times a week for 6 months, during exercise heart rate was monitored by heart rate monitors. The control group (n = 19) did not change their lifestyle during the observed period. All participants passed an all-out bicycle ergometer test to exhaustion and anthropometric measurement (bioelectrical impedance analysis method) before and after this six month program. Results: In the experimental group, after finishing the intervention programme, positive changes were perceptible in almost all monitored parameters; specifically an increase of fat free mass in the lower limbs, peak oxygen consumption, and the duration of the exercise test was statistically significant. Although, in the control group, some monitored parameters changed almost identically; the amount of fat free mass decreased and the duration of the exercise test diminished. Analysis of variance at repeated measurements confirmed that the intervention programme had a statistically significant and positive effect on the duration of the exercise test and on the amount of muscle and fat free mass in the right lower limb. Conclusions: Physical intervention had a statistically important positive influence on the amount of muscle and fat free mass in the right lower limb and on the duration of the exercise test (also logically significant). The results were affected by the women's poor adherence to the aerobics programme, large differences in their motivation and the relatively low training intensity. Despite some inconsistent results, it can be said that an intervention programme in a style of aerobic dance combined with strengh training is suitable physical activity for increasing physical fitness in sedentary middle aged women.

Optimal intensity and type of leg exercise training for people with chronic obstructive pulmonary disease

Intensity of exercise is considered a key determinant of training response, however, no systematic review has investigated the effects of different levels of training intensity on exercise capacity, functional exercise capacity and health-related quality of life (HRQoL) in people with chronic obstructive pulmonary disease (COPD). As type of training (continuous or interval) may also affect training response, the effects of the type of training in COPD also require investigation. To determine the effects of training intensity (higher versus lower) or type (continuous versus interval training) on primary outcomes in exercise capacity and secondary outcomes in symptoms and HRQoL for people with COPD. We searched for studies in any language from the Cochrane Airways Group Specialised Register, CENTRAL, MEDLINE, EMBASE, CINAHL, AMED, PsycINFO and PubMed. Searches were current as of June 2011. We included randomised controlled trials comparing higher training intensity to lower training intensity or comparing continuous training to interval training in people with COPD. We excluded studies that compared exercise training with no exercise training. We pooled results of comparable groups of studies and calculated the treatment effect and 95% confidence intervals (CI) using a random-effects model. We made two separate comparisons of effects between: 1) higher and lower training intensity; 2) continuous and interval training. We contacted authors of missing data. We analysed three included studies (231 participants) for comparisons between higher and lower-intensity training and eight included studies (367 participants) for comparisons between continuous and interval training. Primary outcomes were outcomes at peak exercise (peak work rate, peak oxygen consumption, peak minute ventilation and lactate threshold), at isowork or isotime, endurance time on a constant work rate test and functional exercise capacity (six-minute walk distance). When comparing higher versus lower-intensity training, the pooled primary outcomes were endurance time and six-minute walk distance. There were no significant differences in endurance time improvement (mean difference (MD) 1.07 minutes; 95% CI -1.53 to 3.67) and six-minute walk distance improvement (MD 2.8 metres; 95% CI -10.1 to 15.6) following higher or lower-intensity training. However, heterogeneity of the endurance time results between studies was significant. When comparing continuous and interval training, there were no significant differences in any of the primary outcomes, except for oxygen consumption at isotime (MD 0.08; 95% CI 0.01 to 0.16) but the treatment effect was not considered clinically important. According to the GRADE system, studies were of low to moderate quality. Comparisons between the higher and lower training intensity were limited due to the small number of included studies and participants. Consequently, there are insufficient data to draw any conclusions on exercise capacity, symptoms and HRQoL for this comparison. For comparisons between continuous and interval training, both appear to be equally effective in improving exercise capacity, symptoms and HRQoL.

Training Cadence: New Insight Into Boxing Training

Olympic boxing training is in need of scientific studies to better characterize training intensity to increase quality and performance. Presently, the training sessions are based on empiricism and personal experiences of technical commissions. We propose to use boxing movement cadence to characterize high and low training intensity. PURPOSE: Establish the cadence of movement that characterizes high and low intensity based on internal training load (ITL) and blood lactate concentration (BLC). METHODS: 9 male boxing athletes (18,8±1,75 years old) were submitted to 4 identical (structure and volume) training sessions (TS) as follows: (A) jump rope, punching drills, hanging bag (1 movement per sec); (B) jump rope, punching drills, hanging bag (3 movements per sec). These sessions were considered as low (A) and high (B) intensity and each of them was repeated twice. To determine the ITL, we used the Rating Perceived Exertion (0-10) after 30' post training, and the indicated number was multiplied by TS volume (Foster et al., 2001). BLC was checked before and after TS using Accutrend Lactate (Roche). Lactate concentration was compared between high and low trainings using the Wilcoxon statistic test. RESULTS: The delta of lactate concentration in the low TS (A) was significantly reduced when compared to B. In the same fashion, ITL was also reduced in A when compared to B (table 1). CONCLUSION: The use of cadence (not only structure) of training is key to determine training intensity, which is important for the periodization of training and performance improvement.Table: 1Internal Training Load and Lactate Variation

Influence of exercise intensity in older persons with unchanged habitual nutritional intake: skeletal muscle and endocrine adaptations

Long-term adherence to training programmes is difficult to attain. Yet, the benefits of exercise to general health and well-being are undeniable. Any measure to demonstrate the minimum required exercise for maximal benefit to a person is a promising avenue towards increasing the uptake and adherence to physical activity for the general public. The purpose of this study was to compare the effects of two different intensities of resistance training in healthy older adults. We hypothesised that compared to high-intensity resistance exercise, relatively low training intensity could also improve in vivo markers of healthy physiologic and endocrine functions in previously sedentary older individuals. Thirty (out of a possible 34 recruited) older adults were randomly assigned to low (LowR, i.e. approximately 40% one repetition maximum (1RM)) versus high-resistance training (HighR, i.e. approximately 80% 1RM) for 12 weeks. Neither intervention significantly impacted upon body composition markers including: body mass index (BMI), waist/hip ratio and bioelectric impedance. Muscle strength data showed an advantage for the HighR protocol with 51 +/- 4% and 22.4 +/- 10.2% (P < 0.05) improvements in 1RM strength and bilateral knee extension torque, respectively, compared with 17 +/- 1% and 10.3 +/- 4.7% (P < 0.05) increments in 1RM strength and bilateral torque in the LowR group. Unilateral torque did not change significantly in either group. Quadriceps muscle thickness data also showed a significantly greater benefit of the HighR protocol (5.8 +/- 2.6% increase) compared with the LowR protocol (no change). Functional ability tests, including Get-up-and-go (GUG), Standing from lying and the 6-min walk, showed changes of -11.6 +/- 4.8%, -15.6% and 8.5 +/- 1.7% (P < 0.05), respectively, in HighR compared with only one significant improvement in the LowR, namely a -10.8 +/- 3% (P < 0.05) improvement in the GUG test. Overnight fasting serum levels of IGFBP-3 increased, NPY decreased and TNF-alpha decreased significantly in the LowR group. Serum levels of glucose increased and NPY decreased significantly in HighR. Circulating levels of I, IL-6 and IGF-1 did not change with either intervention. In vivo physiologic changes show functional advantages for older persons carrying out high-resistance training. At the endocrine level, such an advantage is not clear. In fact, in terms of changes in sera levels of fasting glucose, IGFBP-3 and TNF-alpha, there appears to be an advantage to carrying out the lower intensity exercises for the aged populations where endocrine adaptations are key.

Effects of Different Periodization Models on Rate of Force Development and Power Ability of the Upper Extremity

The purpose of our study was to compare the effects of 2 different periodization models on strength and power variables under dynamic and static conditions in the bench press. Participants of the experimental groups were male sport students experienced in weight training (age: 23.98 +/- 3.14 yr). Subjects were tested for the 1 repetition maximum (1RM) in the bench press, maximal movement velocity (Vmax) in the bench press throw (16.9 kg), maximal voluntary contraction (MVC), and maximal rate of force development (MRFD) in 90 degrees elbow and shoulder angle in the isometric bench press. According to their 1RM, subjects were parallelized and assigned to 1 of either 2 training groups: strength-power periodization (SPP, n = 13) or daily undulating periodization (DUP, n = 14). Subjects trained for 14 weeks, 3 days per week. In the strength-power sessions, both groups were instructed to lift the weight as explosively as possible. In addition, a control group (n = 13) was used for comparison. One repetition maximum and Vmax improved significantly through training (p <or= 0.05), with no significant changes in MVC and MRFD. Experimental groups showed no significant group differences in any variable. The results indicate that, in short-term training using previously trained subjects, no differences in 1RM and power are seen between DUP and SPP. As used in our undulating regime, additional training in strength endurance could lead to exhaustion effects and furthermore does not provide an adequate training stimulus for power because of its low training intensity. In spite of this, according to the present findings, it has no negative effect on the application of a neural stimulus that is needed for a strength-power session if adequate regeneration time between workouts is guaranteed.

Training intensity-dependent and tissue-specific increases in lactate uptake and MCT-1 in heart and muscle.

We investigated the effects of 3 wk of moderate- (21 m/min, 8% grade) and highintensity treadmill training (31 m/min, 15% grade) on 1) monocarboxylate transporter 1 (MCT-1) content in rat hindlimb muscles and the heart and 2) lactate uptake in isolated soleus (Sol) muscles and perfused hearts. In the moderately trained group MCT-1 was not increased in any of the muscles [Sol, extensor digitorum longus (EDL), and red (RG) and white gastrocnemius (WG)] (P > 0.05). Similarly, lactate uptake in Sol strips was also not increased (P > 0.05). In contrast, in the heart, MCT-1 (+36%, P < 0.05) and lactate uptake (+72%, P < 0.05) were increased with moderate training. In the highly trained group, MCT-1 (+70%, P < 0.05) and lactate uptake (+79%, P < 0.05) were increased in Sol. MCT-1 was also increased in RG (+94%, P < 0.05) but not in WG and EDL (P > 0.05). In the highly trained group, heart MCT-1 (+44%, P < 0.05) and lactate uptake (+173%, P < 0.05) were increased. In conclusion, it has been shown that 1) in both heart and skeletal muscle lactate uptake is increased only when MCT-1 is increased; 2) training-induced increases in MCT-1 occurred at a lower training intensity in the heart than in skeletal muscle; 3) in the heart, lactate uptake was increased much more after high-intensity training than after moderate-intensity training, despite similar increases in heart MCT-1 with these two training intensities; and 4) the increases in MCT-1 occurred independently of any changes in the heart's oxidative capacity (as measured by citrate synthase activity).

Cellular immunity in highly trained elite racing cyclists during periods of training with high and low intensity

Cellular immunity was measured under resting conditions in 29 highly trained male racing cyclists during a period of low training intensity (winter), and in 15 untrained people. Fifteen of the cyclists were reexamined during a period of high training intensity (summer) together with 10 of the untrained people. Data on lymphocyte subpopulations, natural killer cell activity and lymphocyte proliferative responses were obtained. Changes in any of these immune parameters from low to high training seasons did not differ significantly between the trained and untrained people. The natural killer cell activity was significantly higher in the cyclists, both during the period of low training intensity (39.2±11.6%vs 30.9±6.4%) and during the period of high training intensity (55.2±18.4% vs 33.6±20.3%). Leucocyte, lymphocyte and neutrophil concentrations did not differ between the two groups. The blood mononuclear cell (BMNC) subsets, including CD3+, CD4+, CD8+ and CD16+ cells, and the BMNC proliferative responses following stimulation with either interleukin 2, purified derivative of tuberculin or phytohaemagghitinin did not differ significantly between the groups.