ChatGPT Generated Training Plans for Runners are not Rated Optimal by Coaching Experts, but Increase in Quality with Additional Input Information.

ChatGPT may be used by runners to generate training plans to enhance performance or health aspects. However, the quality of ChatGPT generated training plans based on different input information is unknown. The objective of the study was to evaluate ChatGPT-generated six-week training plans for runners based on different input information granularity. Three training plans were generated by ChatGPT using different input information granularity. 22 quality criteria for training plans were drawn from the literature and used to evaluate training plans by coaching experts on a 1-5 Likert Scale. A Friedmann test assessed significant differences in quality between training plans. For training plans 1, 2 and 3, a median rating of <3 was given 19, 11, and 1 times, a median rating of 3 was given 3, 5, and 8 times and a median rating of >3 was given 0, 6, 13 times, respectively. Training plan 1 received significantly lower ratings compared to training plan 2 for 3 criteria, and 15 times significantly lower ratings compared to training plan 3 (p < 0.05). Training plan 2 received significantly lower ratings (p < 0.05) compared to plan 3 for 9 criteria. ChatGPT generated plans are ranked sub-optimally by coaching experts, although the quality increases when more input information are provided. An understanding of aspects relevant to programming distance running training is important, and we advise avoiding the use of ChatGPT generated training plans without an expert coach's feedback.

The magnitude and time-course of physiological responses to 9 weeks of incremental ramp testing.

PURPOSE: The aims of this study were to assess (1) the day-to-day variability in, and (2) the magnitude and time-course of adaptation of physiological parameters (i.e., maximal oxygen uptake [VO2 max], heart rate [HR], blood lactate concentration, respiratory exchange ratio [RER], ratings of perceived exertion [RPE], and time-to-exhaustion [TTE]) in response to an intervention involving three incremental ramp tests per week for 9 weeks. METHODS: Twelve participants (25 ± 4 yrs, VO2 max, 47.8 ± 5.2 mL∙min-1 ∙kg-1 (means ± SD)) completed the entire experimental procedure. The tests comprised a 5-min constant workload to obtain submaximal parameters followed by an incremental protocol until exhaustion. RESULTS: The mean day-to-day variability for the maximal value of VO2 was 2.8%, 1.1% for HR, 18.1% for blood lactate concentration, 2.1% for RER, 1.1% for RPE, and 5.0% for TTE. The values for the corresponding submaximal variables were 3.8% for VO2 , 2.1% for HR, 15.6% for blood lactate concentration, 2.6% for RER and 6.0% for RPE. VO2 max (+4.7% ± 3.5%), TTE (+17.9% ± 8.6%), and submaximal HR (-3.2 ± 3.5%) improved significantly. Except for RPE (p < 0.01), there were no alterations in the coefficient of variation for any parameter. On the group level, the first changes greater than the day-to-day variability in VO2 max, TTE, and submaximal HR were observed after 21, 12, and 9 training sessions, respectively. CONCLUSION: Based on our findings, we recommend that training studies include assessment of the reliability of the measurements, for example, the CVs in the specific laboratory to be able to judge if the changes detected are actually physiological.

Predefined vs data-guided training prescription based on autonomic nervous system variation: A systematic review.

Monitoring variations in the functioning of the autonomic nervous system may help personalize training of runners and provide more pronounced physiological adaptations and performance improvements. We systematically reviewed the scientific literature comparing physiological adaptations and/or improvements in performance following training based on responses of the autonomic nervous system (ie, changes in heart rate variability) and predefined training. PubMed, SPORTDiscus, and Web of Science were searched systematically in July 2019. Keywords related to endurance, running, autonomic nervous system, and training. Studies were included if they (a) involved interventions consisting predominantly of running training; (b) lasted at least 3 weeks; (c) reported pre- and post-intervention assessment of running performance and/or physiological parameters; (d) included an experimental group performing training adjusted continuously on the basis of alterations in HRV and a control group; and (e) involved healthy runners. Five studies involving six interventions and 166 participants fulfilled our inclusion criteria. Four HRV-based interventions reduced the amount of moderate- and/or high-intensity training significantly. In five interventions, improvements in performance parameters (3000 m, 5000 m, Loadmax, Tlim) were more pronounced following HRV-based training. Peak oxygen uptake ( V ˙ O 2 peak ) and submaximal running parameters (eg, LT1, LT2) improved following both HRV-based and predefined training, with no clear difference in the extent of improvement in V ˙ O 2 peak . Submaximal running parameters tended to improve more following HRV-based training. Research findings to date have been limited and inconsistent. Both HRV-based and predefined training improve running performance and certain submaximal physiological adaptations, with effects of the former training tending to be greater.

Smartwatch-Derived Data and Machine Learning Algorithms Estimate Classes of Ratings of Perceived Exertion in Runners: A Pilot Study.

The rating of perceived exertion (RPE) is a subjective load marker and may assist in individualizing training prescription, particularly by adjusting running intensity. Unfortunately, RPE has shortcomings (e.g., underreporting) and cannot be monitored continuously and automatically throughout a training sessions. In this pilot study, we aimed to predict two classes of RPE ( ≤ 15 "Somewhat hard to hard" on Borg's 6-20 scale vs. RPE > 15 in runners by analyzing data recorded by a commercially-available smartwatch with machine learning algorithms. Twelve trained and untrained runners performed long-continuous runs at a constant self-selected pace to volitional exhaustion. Untrained runners reported their RPE each kilometer, whereas trained runners reported every five kilometers. The kinetics of heart rate, step cadence, and running velocity were recorded continuously ( 1 Hz ) with a commercially-available smartwatch (Polar V800). We trained different machine learning algorithms to estimate the two classes of RPE based on the time series sensor data derived from the smartwatch. Predictions were analyzed in different settings: accuracy overall and per runner type; i.e., accuracy for trained and untrained runners independently. We achieved top accuracies of 84 . 8 for the whole dataset, 81 . 82 for the trained runners, and 86 . 08 for the untrained runners. We predict two classes of RPE with high accuracy using machine learning and smartwatch data. This approach might aid in individualizing training prescriptions.

Post-exercise recovery of contractile function and endurance in humans and mice is accelerated by heating and slowed by cooling skeletal muscle.

KEY POINTS: We investigated whether intramuscular temperature affects the acute recovery of exercise performance following fatigue-induced by endurance exercise. Mean power output was better preserved during an all-out arm-cycling exercise following a 2 h recovery period in which the upper arms were warmed to an intramuscular temperature of Ì´ 38°C than when they were cooled to as low as 15°C, which suggested that recovery of exercise performance in humans is dependent on muscle temperature. Mechanisms underlying the temperature-dependent effect on recovery were studied in intact single mouse muscle fibres where we found that recovery of submaximal force and restoration of fatigue resistance was worsened by cooling (16-26°C) and improved by heating (36°C). Isolated whole mouse muscle experiments confirmed that cooling impaired muscle glycogen resynthesis. We conclude that skeletal muscle recovery from fatigue-induced by endurance exercise is impaired by cooling and improved by heating, due to changes in glycogen resynthesis rate. ABSTRACT: Manipulation of muscle temperature is believed to improve post-exercise recovery, with cooling being especially popular among athletes. However, it is unclear whether such temperature manipulations actually have positive effects. Accordingly, we studied the effect of muscle temperature on the acute recovery of force and fatigue resistance after endurance exercise. One hour of moderate-intensity arm cycling exercise in humans was followed by 2 h recovery in which the upper arms were either heated to 38°C, not treated (33°C), or cooled to ∼15°C. Fatigue resistance after the recovery period was assessed by performing 3 × 5 min sessions of all-out arm cycling at physiological temperature for all conditions (i.e. not heated or cooled). Power output during the all-out exercise was better maintained when muscles were heated during recovery, whereas cooling had the opposite effect. Mechanisms underlying the temperature-dependent effect on recovery were tested in mouse intact single muscle fibres, which were exposed to ∼12 min of glycogen-depleting fatiguing stimulation (350 ms tetani given at 10 s interval until force decreased to 30% of the starting force). Fibres were subsequently exposed to the same fatiguing stimulation protocol after 1-2 h of recovery at 16-36°C. Recovery of submaximal force (30 Hz), the tetanic myoplasmic free [Ca2+ ] (measured with the fluorescent indicator indo-1), and fatigue resistance were all impaired by cooling (16-26°C) and improved by heating (36°C). In addition, glycogen resynthesis was faster at 36°C than 26°C in whole flexor digitorum brevis muscles. We conclude that recovery from exhaustive endurance exercise is accelerated by raising and slowed by lowering muscle temperature.

High-intensity sprint training inhibits mitochondrial respiration through aconitase inactivation.

Intense exercise training is a powerful stimulus that activates mitochondrial biogenesis pathways and thus increases mitochondrial density and oxidative capacity. Moderate levels of reactive oxygen species (ROS) during exercise are considered vital in the adaptive response, but high ROS production is a serious threat to cellular homeostasis. Although biochemical markers of the transition from adaptive to maladaptive ROS stress are lacking, it is likely mediated by redox sensitive enzymes involved in oxidative metabolism. One potential enzyme mediating such redox sensitivity is the citric acid cycle enzyme aconitase. In this study, we examined biopsy specimens of vastus lateralis and triceps brachii in healthy volunteers, together with primary human myotubes. An intense exercise regimen inactivated aconitase by 55-72%, resulting in inhibition of mitochondrial respiration by 50-65%. In the vastus, the mitochondrial dysfunction was compensated for by a 15-72% increase in mitochondrial proteins, whereas H2O2 emission was unchanged. In parallel with the inactivation of aconitase, the intermediary metabolite citrate accumulated and played an integral part in cellular protection against oxidative stress. In contrast, the triceps failed to increase mitochondrial density, and citrate did not accumulate. Instead, mitochondrial H2O2 emission was decreased to 40% of the pretraining levels, together with a 6-fold increase in protein abundance of catalase. In this study, a novel mitochondrial stress response was highlighted where accumulation of citrate acted to preserve the redox status of the cell during periods of intense exercise.

Effect of resistance training with vibration and compression on the formation of muscle and bone.

INTRODUCTION: In this study we investigated the effects of resistance training with vibration in combination with leg compression to restrict blood flow on strength, muscle oxygenation, muscle mass, and bone formation. METHODS: Twelve participants were tested before and after 12 weeks of resistance training with application of vibration (VIBRA; 1-2 mm, 30 Hz) to both legs and compression (∼35 mm Hg, VIBRA+COMP) to only 1 leg. RESULTS: VIBRA+COMP and VIBRA improved 1 repetition maximum (1-RM), increased the number of repetitions preceding muscle exhaustion, enhanced cortical bone mass, and lowered the mass and fat fraction in the thigh, with no changes in total muscle mass. The mass of cancellous bone decreased to a similar extent after VIBRA and VIBRA+COMP. DISCUSSION: Resistance training with VIBRA+COMP and VIBRA improved 1-RM, increased the number of repetitions preceding muscular exhaustion, and enhanced formation of cortical bone, with no alteration of muscle mass. Muscle Nerve 56: 1137-1142, 2017.

Muscle coordination, activation and kinematics of world-class and elite breaststroke swimmers during submaximal and maximal efforts.

The aims of this study were to describe muscular activation patterns and kinematic variables during the complete stroke cycle (SC) and the different phases of breaststroke swimming at submaximal and maximal efforts. Surface electromyography (sEMG) was collected from eight muscles in nine elite swimmers; five females (age 20.3 ± 5.4 years; Fédération Internationale de Natation [FINA] points 815 ± 160) and four males (27.7 ± 7.1 years; FINA points 879 ± 151). Underwater cameras were used for 3D kinematic analysis with automatic motion tracking. The participants swam 25 m of breaststroke at 60%, 80% and 100% effort and each SC was divided into three phases: knee extension, knee extended and knee flexion. With increasing effort, the swimmers decreased their SC distance and increased their velocity and stroke rate. A decrease during the different phases was found for duration during knee extended and knee flexion, distance during knee extended and knee angle at the beginning of knee extension with increasing effort. Velocity increased for all phases. The mean activation pattern remained similar across the different effort levels, but the muscles showed longer activation periods relative to the SC and increased integrated sEMG (except trapezius) with increasing effort. The muscle activation patterns, muscular participation and kinematics assessed in this study with elite breaststroke swimmers contribute to a better understanding of the stroke and what occurs at different effort levels. This could be used as a reference for optimising breaststroke training to improve performance.

Topical application of cream containing nonivamide and nicoboxil does not enhance the performance of experienced cyclists during a 4-km time-trial.

PURPOSE: Topical application of nonivamide-nicoboxil cream to resting legs has been shown to enhance the level of oxygenated haemoglobin in leg muscles 15 min later. Here, we examined whether such application improves the performance of experienced cyclists in a subsequent 4-km time-trial. METHODS: Nine male cyclists [26 ± 8 years; 176 ± 9 cm; 73.5 ± 12.8 kg; peak oxygen uptake: 50.7 ± 4.0 mL min(-1) kg(-1) (mean ± SD)] performed three 4-km time-trials on an ergometer with either topical application of nonivamide-nicoboxil cream (CREAM) or cream without active components (SHAM) to both their thigh muscles or no application (CONTROL). RESULTS: Only the skin temperature immediately before and after the time-trial was higher with cream than SHAM and CONTROL (best p < 0.001, best d = 1.16). All other parameters evaluated, i.e., the average power output during the time-trial (p > 0.05, best d = 0.08), the tissue saturation index of the m. vastus lateralis (p > 0.05, best d = 0.57), cardiac output, heart rate, oxygen uptake, blood lactate concentration, and perceived exertion (p > 0.05, best d = 1.1) were similar under all three conditions. CONCLUSIONS: Our present findings reveal that topical application of cream containing nonivamide and nicoboxil to the thighs of cyclists prior to a 4-km time-trial does not improve their power output, saturation of the m. vastus lateralis with oxygen, oxygen uptake, heart rate, cardiac parameters, or perceived level of exertion.

Low energy availability in exercising men is associated with reduced leptin and insulin but not with changes in other metabolic hormones.

Low energy availability, defined as low caloric intake relative to exercise energy expenditure, has been linked to endocrine alterations frequently observed in chronically energy-deficient exercising women. Our goal was to determine the endocrine effects of low energy availability in exercising men. Six exercising men (VO2peak: 49.3 ± 2.4 ml · kg(-1) · min(-1)) underwent two conditions of low energy availability (15 kcal · kg(-1) fat-free mass [FFM] · day(-1)) and two energy-balanced conditions (40 kcal · kg(-1) FFM · day(-1)) in randomised order. During one low energy availability and one balanced condition, participants exercised to expend 15 kcal · kg(-1) FFM · day(-1); no exercise was conducted during the other two conditions. Metabolic hormones were assessed before and after each 4-day period. Following both low energy availability conditions, leptin (-53% to -56%) and insulin (-34% to -38%) were reduced (P < 0.05). Reductions in leptin and insulin were independent of whether low energy availability was attained with or without exercise (P > 0.80). Low energy availability did not significantly impact ghrelin, triiodothyronine, testosterone and IGF-1 (all P > 0.05). The observed reductions in leptin and insulin were in the same magnitude as changes previously reported in sedentary women. Further research is needed to understand why other metabolic hormones are more robust against low energy availability in exercising men than those in sedentary and exercising women.

Effects of Loaded Squat Exercise with and without Application of Superimposed EMS on Physical Performance.

The aim of the present study was to investigate the effects of a multiple set squat exercise training intervention with superimposed electromyostimulation (EMS) on strength and power, sprint and jump performance. Twenty athletes from different disciplines participated and were divided into two groups: strength training (S) or strength training with superimposed EMS (S+E). Both groups completed the same training program twice a week over a six week period consisting of four sets of the 10 repetition maximum of back squats. Additionally, the S+E group had EMS superimposed to the squat exercise with simultaneous stimulation of leg and trunk muscles. EMS intensity was adjusted to 70% of individual pain threshold to ensure dynamic movement. Strength and power of different muscle groups, sprint, and vertical jump performance were assessed one week before (pre), one week after (post) and three weeks (re) following the training period. Both groups showed improvements in leg press strength and power, countermovement and squat jump performance and pendulum sprint (p < 0.05), with no changes for linear sprint. Differences between groups were only evident at the leg curl machine with greater improvements for the S+E group (p < 0.05). Common squat exercise training and squat exercise with superimposed EMS improves maximum strength and power, as well as jumping abilities in athletes from different disciplines. The greater improvements in strength performance of leg curl muscles caused by superimposed EMS with improvements in strength of antagonistic hamstrings in the S+E group are suggesting the potential of EMS to unloaded (antagonistic) muscle groups. Key pointsSimilar strength adaptations occurred after a 6 week 10 RM back squat exercise program with superimposed EMS (S+E) and 10 RM back squat exercise (S) alone.Specific adaptations for S+E at the leg curl muscles were evident.S and S+E improved SJ, CMJ and pendulum sprint performance.No improvement occurred in linear sprint performance.

Multi-Directional Sprint Training Improves Change-Of-Direction Speed and Reactive Agility in Young Highly Trained Soccer Players.

The aim of this study was to evaluate the effect of a repeated sprint training with multi-directional change-of-direction (COD) movements (RSmulti) compared to repeated shuttle sprints (RSS) on variables related to COD speed and reactive agility. Nineteen highly-trained male U15 soccer players were assigned into two groups performing either RSmulti or RSS. For both groups, each training session involved 20 repeated 15 s sprints interspersed with 30 s recovery. With RSmulti the COD movements were randomized and performed in response to a visual stimulus, while the RSS involved predefined 180° COD movements. Before and following the six training sessions, performance in the Illinois agility test (IAT), COD speed in response to a visual stimulus, 20 m linear sprint time and vertical jumping height were assessed. Both groups improved their performance in the IAT (p < 0.01, ES = 1.13; p = 0.01, ES = 0.55). The COD speed in response to a visual stimulus improved with the RSmulti (p < 0.01, ES = 1.03), but not the RSS (p = 0.46, ES = 0.28). No differences were found for 20 m sprint time (P=0.73, ES = 0.07; p = 0.14, ES = 0.28) or vertical jumping height (p = 0.46, ES = 0.11; p = 0.29, ES = 0.12) for the RSmulti and RSS, respectively. In conclusion, performance in the IAT improved with the RSmulti as well as RSS. With the RSmulti however, the COD movements are performed in response to a visual stimulus, which may result in specific adaptations that improve COD speed and reactive agility in young highly trained soccer players. Key pointsDuring soccer, the players perform repeated sprints involving multi-directional COD movements, while most of these turns and twists are not pre-planned but executed in response to an external stimulus, such as ball movement, several interacting opponents and changing game situations.Both groups improved performance in the IAT. With the RSmulti on the Speedcourt however, the COD movements are performed in response to a visual stimulus, which may result in specific adaptations that improve COD speed and reactive agility.The Speedcourt could serve as a valuable method to design and individualize specific conditioning drills for young highly-trained soccer players.

Repeated apnea-induced contraction of the spleen in cyclists does not enhance performance in a subsequent time-trial.

PURPOSE: Splenic contraction induced by repeated apneas has been shown to increase oxygen availability. Our aim was to determine whether repeated maximal voluntary apnea enhances the performance of cyclists in a subsequent 4-km time trial. METHODS: Seven male cyclists [age: 27.1 ± 2.1 years; height: 182 ± 8 cm; body mass: 74.8 ± 9.2 kg; peak oxygen uptake: 56.9 ± 6.6 mL min(-1) kg(-1) (mean ± SD)] performed a 4-km time trial on an ergometer with and without four prior maximal bouts of apnea interspersed with 2 min of recovery. RESULTS: The average power output during the time trial was similar with (293 ± 48 W) and without (305 ± 42 W) prior apnea (P = 0.11, d = 0.27). The spleen was reduced in size after the fourth bout of apnea (-12.4 ± 9.0 %), as well as one (-36.6 ± 10.3 %) and 10 min (-19.5 ± 17.9 %) after the time trial, while with normal breathing the spleen was smaller one (-35.0 ± 11.3 %) and 10 min (-23.4 ± 19.7 %) after the time trial. Heart rate; oxygen uptake and carbon dioxide production; tissue oxygen saturation; and the lactate concentration, pH, oxygen saturation, level of hemoglobin and hematocrit of the blood were similar under both conditions. CONCLUSIONS: Our present findings reveal that four apneas by cyclists prior to a 4-km time trial led to splenic contraction, but no change in mean power output, the level of hemoglobin, hematocrit, oxygen saturation of the m. vastus lateralis or oxygen uptake.

Individual versus Standardized Running Protocols in the Determination of VO2max.

The purpose of this study was to determine whether an individually designed incremental exercise protocol results in greater rates of oxygen uptake (VO2max) than standardized testing. Fourteen well-trained, male runners performed five incremental protocols in randomized order to measure their VO2max: i) an incremental test (INCS+I) with pre-defined increases in speed (2 min at 8.64 km·h(-1), then a rise of 1.44 km·h(-1) every 30 s up to 14.4 km·h(-1)) and thereafter inclination (0.5° every 30 s); ii) an incremental test (INCI) at constant speed (14.4 km·h(-1)) and increasing inclination (2° every 2 min from the initial 0°); iii) an incremental test (INCS) at constant inclination (0°) and increasing speed (0.5 km·h(-1) every 30 s from the initial 12.0 km·h(-1)); iv) a graded exercise protocol (GXP) at a 1° incline with increasing speed (initially 8.64 km·h(-1) + 1.44 km·h(-1) every 5 min); v) an individual exercise protocol (INDXP) in which the runner chose the inclination and speed. VO2max was lowest (-4.2%) during the GXP (p = 0.01; d = 0.06-0.61) compared to all other tests. The highest rating of perceived exertion, heart rate, ventilation and end-exercise blood lactate concentration were similar between the different protocols (p < 0.05). The time to exhaustion ranged from 7 min 18 sec (INCS) to 25 min 30 sec (GXP) (p = 0.01).The VO2max attained by employing an individual treadmill protocol does not differ from the values derived from various standardized incremental protocols. Key pointsThe mean maximum oxygen uptake during the GXP was lower than for all other tests.Differences in the maximum rate of oxygen uptake between the various protocols exhibited considerable inter-individual variation.From the current findings, it can be concluded that well trained athletes are able to perform an individually designed treadmill running protocol.

Cardiorespiratory Markers Relate to Change-of-Direction Performance During Incremental Endurance Tests and Friendly Matches in Professional Male Handball Players.

PURPOSE: To compare the standard Yo-Yo intermittent recovery (IR) test and an agility Yo-Yo IR test with a higher number of change-of-direction movements to cardiorespiratory match performance. METHODS: The study included 11 professional male handball players (age 24.5 [4.6] y) of a German second-league team. The performance parameters of the players of the seasons 2016-17 to 2018-19 were analyzed. The Yo-Yo IR test was compared to a Yo-Yo IR test with multiple multidirectional changes of direction in response to visual stimuli, which was conducted on a SpeedCourt (Yo-Yo SC IR). Peak oxygen uptake (VO2peak) and maximum heart rate (HRmax) were measured. Between-methods differences of individual athletes were quantified with Bland-Altman plots. RESULTS: HRmax was not statistically different during the Yo-Yo SC IR test compared to the Yo-Yo IR test (181 [10] vs 188 [8] beats·min-1; P = .16). Agreement between the 2 tests was moderate for HRmax and good for heart rates >180 beats·min-1. Mean average VO2peak was 51.7 (3.9) and 50.9 (2.8) mL·min-1·kg-1 for the Yo-Yo SC IR test and the Yo-Yo IR test (P = .693), respectively. CONCLUSIONS: A Yo-Yo test with multidirectional changes of direction in response to visual stimuli yielded good agreement with the frequently used linear running tests and can be used to assess players' VO2peak. The HRmax achieved during this test should be used with caution.

Passive recovery is superior to active recovery during a high-intensity shock microcycle.

The purpose was to examine the effects of a 2-week high-intensity shock microcycle on maximal oxygen consumption and parameters of exercise performance in junior triathletes on the one hand and to evaluate the long-term effects of active (A) vs. passive (P) recovery on the other hand. Sixteen healthy junior triathletes participated in the study. For the assignment to the A or P group, the subjects were matched according to age and performance. Within 2 weeks, a total of 15 high-intensity interval sessions within three 3-day training blocks were performed. Before and 1 week after the last training session, the athletes performed a ramp test to determine V[Combining Dot Above]O2max, a time trial (TT) and a Wingate test. Furthermore, total hemoglobin (Hb) mass was determined. The results of the whole group, independent of the arrangement of recovery, were analyzed at first; second, the A and P groups were analyzed separately. Peak power output (PPO) during the ramp test and TT performance significantly increased in the whole group. The comparison of the 2 groups revealed increases for the mentioned parameters and for V[Combining Dot Above]O2 and power output at VT2 for the P group only. The V[Combining Dot Above]O2max did not change. Wingate performance increased in the A group only. The tHb mass slightly decreased. The main finding of this study was that a 14-day shock microcycle is able to improve TT performance and PPO in junior triathletes in a short period of time. Furthermore, not only the intensity but also the arrangement of interval training seems to be important as well, because only the P group showed improvements in endurance performance, despite a slightly lower training volume. These findings might be relevant for future arrangements of high-intensity interval training.

Muscle strength gains per week are higher in the lower-body than the upper-body in resistance training experienced healthy young women-A systematic review with meta-analysis.

BACKGROUND: Women are underrepresented in resistance exercise-related studies. To date only one meta-analysis provides concrete training recommendations for muscle strength gains through resistance training in eumenorrhoeic women. OBJECTIVE: This review aims to identify research gaps to advance future study in this area to expand the knowledge concerning resistance exercise-induced strength gains in women and to provide guidelines on the number of repetitions per set and the training frequency per week to enhance maximal muscle strength. METHODS: The electronic databases PubMed and Web of Science were searched using a comprehensive list of relevant terms. After checking for exclusion criteria, 31 studies could be included in the final analysis using data from 621 subjects. From these data sets, the ideal number of repetitions per set and also the training frequency per week were analyzed. RESULTS: In the lower body, the largest gains were achieved with 1 to 6 repetitions (17.4% 1RM increase). For lower-body exercises, the highest gains were achieved with 13 to 20 repetitions (8.7% 1RM increase). The lower body should be trained two times a week (8.5% 1RM increase). The upper body should be trained two (5.2% 1RM increase) to three times (4.5% 1RM increase) a week. CONCLUSION: Women can increase their 1RM by 7.2% per week in the upper body and by 5.2% per week in the lower-body exercises. The upper body can be trained more than two times per week whereas the lower body should be trained two times. Women with intermediate experiences in RT and advanced performance level show more rapid increases in strength in the lower-body compared to the upper-body while no differences were found between upper and lower limb adaptations in RT-beginner subjects.

Corrigendum: Position statement and updated international guideline for safe and effective whole-body electromyostimulation training-the need for common sense in WB-EMS application.

[This corrects the article DOI: 10.3389/fphys.2023.1174103.].

Position statement and updated international guideline for safe and effective whole-body electromyostimulation training-the need for common sense in WB-EMS application.

Whole-Body Electromyostimulation (WB-EMS) is a training technology that enables simultaneous stimulation of all the main muscle groups with a specific impulse intensity for each electrode. The corresponding time-efficiency and joint-friendliness of WB-EMS may be particularly attractive for people unable or unmotivated to conduct (intense) conventional training protocols. However, due to the enormous metabolic and musculoskeletal impact of WB-EMS, particular attention must be paid to the application of this technology. In the past, several scientific and newspaper articles reported severe adverse effects of WB-EMS. To increase the safety of commercial non-medical WB-EMS application, recommendations "for safe and effective whole-body electromyostimulation" were launched in 2016. However, new developments and trends require an update of these recommendations to incorporate more international expertise with demonstrated experience in the application of WB-EMS. The new version of these consensus-based recommendations has been structured into 1) "general aspects of WB-EMS", 2) "preparation for training", recommendations for the 3) "WB-EMS application" itself and 4) "safety aspects during and after training". Key topics particularly addressed are 1) consistent and close supervision of WB-EMS application, 2) mandatory qualification of WB-EMS trainers, 3) anamnesis and corresponding consideration of contraindications prior to WB-EMS, 4) the participant's proper preparation for the session, 5) careful preparation of the WB-EMS novice, 6) appropriate regeneration periods between WB-EMS sessions and 7) continuous interaction between trainer and participant at a close physical distance. In summary, we are convinced that the present guideline will contribute to greater safety and effectiveness in the area of non-medical commercial WB-EMS application.