The Polar OH1 is an optical heart rate (HR) sensor which can be used on different parts of the body. The purpose of the study was to evaluate the validity of the OH1 as well as a wrist worn heart ...rate device (Polar M600) during swimming.
Twenty-six well-trained competitive swimmers performed a regular training session including different swimming intensities. During the training the swimmers wore a H10 HR sensor with Polar Pro strap (H10) underneath the swim suit, a Polar OH1 optical HR sensor (OH1) underneath the swimming cap at the temple, and a sports watch with optical HR sensor, Polar M600 smart watch (M600) on the wrist.
No difference in HRmax, HRmean and HRmin between H10 and OH1 were evident. The HRmax and HRmean obtained by the M600 was significantly lower than the obtained by H10 and OH1 (p < 0.05). The ICC showed mostly excellent agreements between H10 and OH1 and poor to good agreements between H10 and M600. Bland-Altmann plot for M600 vs. H10 indicates upper and lower limits of agreement of -53.0 to 33.9 beats per minute. For OH1 vs. H10 the upper and lower limits of agreement were -26.9 to 24.7 beats per minute.
The Polar OH1 optical HR sensor is a valid tool to monitor HR of different intensities during swimming whereas the Polar M600 smart watch as a wrist worn device is less accurate.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
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.
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.
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.
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Gavanda, S, Isenmann, E, Geisler, S, Faigenbaum, A, and Zinner, C. The effects of high-intensity functional training compared with traditional strength or endurance training on physical ...performance in adolescents: a randomized controlled trial.
J Strength Cond Res
36(3): 624–632, 2022—High-intensity functional training (HIFT) integrates different modes of exercise into training sessions performed at a relatively high intensity. Although HIFT is becoming more popular in youth strength and conditioning programs, research comparing the effects of HIFT with traditional forms of training, such as strength training (ST) or endurance training (ET) in younger populations are limited. Therefore, the aim of this study was to compare the effects of HIFT with those of ST and ET on strength and endurance performance in adolescents. Fifty-two untrained adolescents (
JOURNAL/jscr/04.03/00124278-202203000-00005/5FFU1/v/2023-10-16T001806Z/r/image-tiff
= 26;
JOURNAL/jscr/04.03/00124278-202203000-00005/5FFU2/v/2023-10-16T001806Z/r/image-tiff
= 26; 17.3 ± 1.0 years) were randomly assigned to a HIFT, ST, ET, or control group. The intervention groups trained twice a week for 6 weeks with a training duration of 60–75 minutes per session. Performance was assessed before and after the intervention with the countermovement jump (CMJ), 20-m sprint (20 m), 3-repetition maximum back squat (3RM), and Yo-Yo test. The HIFT group made significant improvements in all performance tests (CMJ, +28.5 ± 27.6%;
p
> 0.001; 20-m time, −3.9 ± 5.0%;
p
= 0.002; 3RM, +34.3 ± 23.3%;
p
> 0.001; Yo-Yo, +14.5 ± 15.2%;
p
= 0.003), whereas the ST group improved in CMJ (+38.3 ± 27.7%;
p
> 0.001), 3RM (+22.2 ± 11.2%;
p
> 0.001), and Yo-Yo (+12.2 ± 21.4%;
p
= 0.013) and the ET group improved in CMJ (+23.4 ± 29.9%;
p
= 0.001), 20-m time (−5.2 ± 4.6%;
p
> 0.001), and Yo-Yo (+30.7 ± 37.3%;
p
> 0.001). No significant differences between the groups were evident when the results were compared for sex. These results indicate that HIFT is an effective training method for eliciting multifaceted improvements in strength, power, and endurance measures as compared with ET or ST alone in untrained adolescents.
The aim of this study was to investigate inter-day and -week as well as intra- and inter-individual variation of selected biomarkers in high-performance youth soccer players to assist practitioners ...interpreting player’s internal load to counteract underperformance and unwanted health risks. Eleven male youth soccer players were tested multiple times during two 3-week periods at midpoint (3-wk
mid
) and at the end (3-wk
end
) of the first half of a German under-19 1. Bundesliga season. The levels of creatine kinase (CK), urea, and C-reactive protein (CRP) were measured during 3-wk
mid
and 3-wk
end
each Monday, Wednesday, and Friday. In 3-wk
mid
the CK median was 14% higher (241 vs. 212 U/L) compared to 3-wk
end
(
P
= 0.26, ES = 0.16). Overall, the medians of CK, urea (
P
= 0.59, ES = 0.08), and CRP (
P
= 0.56, ES = 0.10) during 3-wk
mid
did not differ to the values of 3-wk
end
. Daily coefficient of variations (CVs) ranged from 22 to 71% (CK), 17 to 37% (urea), and 9 to 164% (CRP). Individual medians ranged from 101 to 350 U/L (CK), 23 to 50 mg/dL (urea), and 0.6 to 1.1 mg/L (CRP). High intra-individual variability was demonstrated by large intra-individual CVs (medians: CK 50%, urea 18%, and CRP 45%). Our data show (i) large inter-day and inter-week variability of all biomarkers, depending on the external load and (ii) considerable inter- and intra-individual parameter variations. Creatine kinase concentrations could sensitively reflect soccer-specific loads during the season.
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 ̴ 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.
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.
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 ̴ 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.
Police officers are often required to perform under high-stress circumstances, in which optimal task performance is crucial for their and the bystanders' physical integrity. However, stress ...responses, particularly anxiety and increased cortisol levels, shift attention from goal-directed to stimulus-driven control, leaving police officers with poor shooting performance under stress. Cardiac vagal activity and coping-related traits (i.e., self-control, sensation seeking) might help individuals to maintain performance under stress. So far, only few studies have integrated coping-related traits, psychophysiological stress markers and occupationally meaningful measures of behavior to investigate police officers' work performance under stress. Therefore, the present study investigated 19 police recruits (
= 22.84,
= 3.30) undergoing a reality-based shooting scenario in two experimental conditions in a within-design: low stress (LS) against a non-threatening mannequin, and high stress (HS), involving physical threat by an opponent. Psychological (i.e., anxiety, mental effort) and physiological stress responses (i.e., salivary cortisol, alpha-amylase, cardiac vagal activity) as well as shooting accuracy were repeatedly assessed. It was hypothesized that under stress, police recruits would demonstrate elevated psychophysiological stress responses and impaired shooting performance. Elevated psychophysiological stress responses would negatively influence shooting performance, whereas self-control, sensation seeking and cardiac vagal activity would positively influence shooting performance. While recruits reported significantly higher anxiety and mental effort in the HS scenario, both scenarios elicited comparable physiological responses. Overall, shooting accuracy was low and did not significantly decrease in the HS scenario. Shooting performance was predicted by self-control in the LS scenario and by post-task cardiac vagal activity in the HS scenario. While increased anxiety hints at a successful stress manipulation, physiological responses suggest similar stress levels for both scenarios, diminishing potential behavioral differences between the scenarios. Performance efficiency decreased under stress, as indicated by increasing mental effort. Findings on self-control suggest that suppressing negative stress responses might lead to impaired goal-directed attention, resulting in performance decrements. For police research and training, high-realism scenarios afford an opportunity to investigate and experience psychophysiological stress responses.
ABSTRACT
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.—Larsen, F. J., Schiffer, T. A., Ørtenblad, N., Zinner, C., Morales‐Alamo, D., Willis, S. J., Calbet, J. A., Holmberg, H.‐C., Boushel, R. High‐intensity sprint training inhibits mitochondrial respiration through aconitase inactivation. FASEB J. 30, 417‐427 (2016). www.fasebj.org
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.
Background
Research results on the training intensity distribution (TID) in endurance athletes are equivocal. This non-uniformity appears to be partially founded in the different quantification ...methods that are implemented. So far, TID research has solely focused on sports involving the lower-body muscles as prime movers (e.g. running). Sprint kayaking imposes high demands on the upper-body endurance capacity of the athlete. As there are structural and physiological differences between upper- and lower-body musculature, TID in kayaking should be different to lower-body dominant sports. Therefore, we aimed to compare the training intensity distribution during an 8-wk macrocycle in a group of highly trained sprint kayakers employing three different methods of training intensity quantification.
Methods
Heart rate (HR) and velocity during on-water training of nine highly trained German sprint kayakers were recorded during the final 8 weeks of a competition period leading to the national championships. The fractional analysis of TID was based on three zones (Z) derived from either HR (TID
Bla-HR
) or velocity (TID
Bla-V
) based on blood lactate (B
la
) concentrations (Z1 ≤ 2.5 mmol L
−1
B
la
, Z2 = 2.5–4.0 mmol L
−1
B
la
, Z3 ≥ 4.0 mmol L
−1
B
la
) of an incremental test or the 1000-m race pace (TID
Race
): Z1 ≤ 85% of race pace, Z2 = 86–95% and Z3 ≥ 95%.
Results
TID
Bla-V
(Z1: 68%, Z2: 14%, Z3: 18%) differed from TID
Bla-HR
(Z1: 91%, Z2: 6%, Z3: 3%) in each zone (all
p
< 0.01). TID
Race
(Z1: 73%, Z2: 20%, Z3: 7%) differed to Z3 in TID
Bla-V
(
p
< 0.01) and all three TID
Bla-HR
zones (all
p
< 0.01). Individual analysis revealed ranges of Z1, Z2, Z3 fractions for TID
Bla-HR
of 85–98%, 2–11% and 0.1–6%. For TID
Bla-V
, the individual ranges were 41–82% (Z1), 6–30% (Z2) and 8–30% (Z3) and for TID
Race
64–81% (Z1), 14–29% (Z2) and 4–10% (Z3).
Conclusion
The results show that the method of training intensity quantification substantially affects the fraction of TID in well-trained sprint kayakers. TID
Race
determination shows low interindividual variation compared to the physiologically based TID
Bla-HR
and TID
Bla-V
. Depending on the aim of the analysis TID
Race
, TID
Bla-HR
and TID
Bla-V
have advantages as well as drawbacks and may be implemented in conjunction to maximize adaptation.
The aim of the study was to evaluate the mucosal immune function and circadian variation of salivary cortisol, Immunoglobin-A (sIgA) secretion rate and mood during a period of high-intensity interval ...training (HIIT) compared to long-slow distance training (LSD).
Recreational male runners (
= 28) completed nine sessions of either HIIT or LSD within 3 weeks. The HIIT involved 4 × 4 min of running at 90-95% of maximum heart rate interspersed with 3 min of active recovery while the LSD comprised of continuous running at 70-75% of maximum heart rate for 60-80 min. The psycho-immunological stress-response was investigated with a full daily profile of salivary cortisol and immunoglobin-A (sIgA) secretion rate along with the mood state on a baseline day, the first and last day of training and at follow-up 4 days after the last day of training. Before and after the training period, each athlete's running performance and peak oxygen uptake (V
O
) was determined with an incremental exercise test.
The HIIT resulted in a longer time-to-exhaustion (
= 0.02) and increased V
O
compared to LSD (
= 0.01). The circadian variation of sIgA secretion rate showed highest values in the morning immediately after waking up followed by a decrease throughout the day in both groups (
< 0.05). With HIIT, the wake-up response of sIgA secretion rate was higher on the last day of training (
< 0.01) as well as the area under the curve (AUC
) higher on the first and last day of training and follow-up compared to the LSD (
= 0.01). Also the AUC
for the sIgA secretion rate correlated with the increase in V
O
and running performance. The AUC
for cortisol remained unaffected on the first and last day of training but increased on the follow-up day with both, HIIT and LSD (
< 0.01).
The increased sIgA secretion rate with the HIIT indicates no compromised mucosal immune function compared to LSD and shows the functional adaptation of the mucosal immune system in response to the increased stress and training load of nine sessions of HIIT.
PDF
