Short Rest Research Articles

Effects of Resistance Circuit-Based Training on Body Composition, Strength and Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis.

Simple SummaryResistance circuit-based training is an effective training method to decrease total body fat and increase muscle mass in adults. Resistance circuit-based training promotes concurrent improvements in strength performance and cardiorespiratory fitness variables in adults. If training load is managed properly, a greater effect on body composition and strength adaptations is possible. Regarding 1-RM improvements, the effect of this type of training is influenced by the training status, obtaining greater effects in untrained and active adults, and by the training characteristics, showing a larger effect in protocols with three sessions and a duration of >20 training sessions. For body fat mass decreases, the effect of resistance circuit-based training was significantly greater in protocols that used low (<60% 1-RM) or moderate intensity (60–80% 1-RM) and short periods or rest between exercises (10–30 s).We assessed the effects of resistance circuit-based training (CT) on strength, cardiorespiratory fitness, and body composition. A systematic review with meta-analysis was conducted in three databases, ending on March, 2020. Meta-analysis and subgroup analysis were used to analyze the effects of pre–post-intervention CT and differences from control groups (CG). Of the 830 studies found, 45 were included in the meta-analysis (58 experimental groups (n = 897) and 34 CG (n = 474)). The CT interventions led to increases in muscle mass (1.9%; p < 0.001) and decreases in fat mass (4.3%; p < 0.001). With regard to cardiorespiratory fitness, CT had a favorable effect on VO2max (6.3%; p < 0.001), maximum aerobic speed or power (0.3%; p = 0.04), and aerobic performance (2.6%; p = 0.006) after training. Concerning strength outcome, the CT increased the strength of the upper and lower extremities. Only the magnitude of strength performance appears to be influenced by the training (number of sessions and frequency) and the training status. Moreover, low and moderate intensities and short rest time between exercise increase the magnitude of change in fat mass loss. Therefore, CT has been shown to be an effective method for improving body composition, cardiorespiratory fitness, and strength of the lower and upper limbs.

Preliminary Safety and Efficacy of Head and Neck Cooling Therapy After Concussion in Adolescent Athletes: A Randomized Pilot Trial.

Objective:To determine the safety and efficacy of head and neck cooling when applied up to 8 days after concussion among adolescent athletes.Design:A randomized nonblinded pilot trial.Setting:Sports Medicine Clinic in a tertiary hospital.Patients:Adolescent athletes aged 12 to 17 years diagnosed with a concussion within 1 week of injury.Interventions and Main Outcome Measures:The control group (n = 27) received standard treatment (short term brain rest), whereas the treatment group (n = 28) received standard treatment and head and neck cooling. Head and neck cooling treatment was applied to patients at the postinjury assessment visit and at 72 hours post-injury. The SCAT5 (Sport Concussion Assessment Tool) total symptom severity score was collected at postinjury assessment visit, pre- and post-treatment at 72 hours, and at 10 days, and 4 weeks post-treatment.Results:Athletes who received head and neck cooling had a faster symptom recovery (P = 0.003) and experienced significant reduction in symptom severity scores after treatment (P < 0.001). Sport type and gender did not influence the treatment outcome (P = 0.447 and 0.940, respectively).Conclusions:This pilot study demonstrates feasibility of head and neck cooling for the management of acute concussion in adolescent athletes.

Intake of branched chain amino acids favors post-exercise muscle recovery and may improve muscle function: optimal dosage regimens and consumption conditions.

Numerous sportspeople consume nutritional ergogenic aids, including branched chain amino acids (BCAA), considered to favor post-exercise muscle recovery. The purpose of this study was to assess the effect of BCAA on recovery from muscle damage produced by high-intensity exercise and muscle function. This allowed to define the optimal dosage regimen and consumption conditions taking into account the combination of BCAA with other products. A systematic review of the scientific literature published over the past 15 years using the PubMed/MEDLINE, Scopus and Web of Science databases was carried out. Nineteen articles were selected. The most optimal regimen for post-exercise muscle recovery and/or muscle function after high-intensity resistance exercise was 2-10 g BCAA/day (leucine: isoleucine: valine at 2:1:1), consumed as a supplement alone or combined with arginine and carbohydrates, 3 previous days before exercise, immediately before and after exercise, regardless of training level. This treatment can improve perceived muscle damage, fatigue, circumference of arm/leg, counter movement jump, maximum muscle strength and maximum voluntary contraction, and reduce creatine kinase and lactate dehydrogenase levels, mainly in young males. Intake of BCAA favors post-exercise muscle recovery and may improve muscle function. The present review can serve as a guidance for high intensity endurance athletes who need to reduce post-exercise muscle damage and maintain or improve muscle function, especially in training periods and competition events planned with short rest periods.

Structural and functional indicators of the heart of patients with ischemic heart disease and type 2 diabetes mellitus. Rhythmoinotropic response isolated myocardium at different levels of glycated hemoglobin

BACKGROUND: Adequate glycemic control can significantly reduce the risk of developing cardiovascular events. However, until now, glycaemic targets in aged patients remain a subject of discussion, especially in the conditions of the combined development of Type 2 Diabetes Mellitus (T2DM) and ischemic heart disease (IHD).AIMS: To examine the structural and functional heart parameters in patients with IHD associated with T2DM and the rhythmoinotropic responses of their isolated myocardium depending on glycated hemoglobin level.MATERIALS AND METHODS: The study included 44 patients with a diagnosis of "chronic IHD associated with T2DM", of which 2 groups were formed. Patients with glycated hemoglobin level (HbA1c) &lt;8% were included in the 1st group, and patients with HbA1c ≥8% were included in the 2nd group. The structural and functional heart parameters obtained with ultrasonography, and the rhythmoinotropic responses of myocardium in patients ex vivo were analyzed using the right atrial appendage fragments obtained during elective coronary artery bypass graft. The inotropic response of muscle strips at a basic stimulation frequency of 0,5 Hz to testing influences was assessed. An extrasystolic test and post-rest test were performed.RESULTS: It was found that extrasystolic contractions of isolated myocardial strips in patients of the 2nd group appeared at shorter extrasystolic intervals, which indicates a greater excitability of the myocardium in patients of this group. Postextrasystolic muscle contractions in patients of the 2nd group had significant potentiation. The amplitude of the muscle strips contractions in patients of both groups was potentiative after short rest periods. However, with an increase in the rest duration, potentiation of contractions was observed only in the group with a higher HbA1c level. According to the ultrasonography data, it was found that the values of the endsystolic and diastolic volumes, the interventricular septum thickness and the left ventricular (LV) myocardium mass were significantly lower in the patients of the 1st group compared with the corresponding indicators in the patients of the 2nd group. The early LV filling velocity (peak E) was significantly lower in the patients of the 1st group, which indicates a slower LV relaxation. At the same time, the rapid LV filling velocity did not have a significant intergroup difference, but this indicator exceeded the reference values in both groups.CONCLUSIONS: With a moderately increased glycemic level (9,2 [8,0; 10,3]%), the structural and functional heart parameters are preserved both at the level of the isolated myocardial tissue and at the level of the whole heart.

Effects of Pre-Activation with Variable Intra-Repetition Resistance on Throwing Velocity in Female Handball Players: a Methodological Proposal.

The purpose of this study was to investigate the acute effect of pre-activation with Variable Intra-Repetition Resistance and isometry on the overhead throwing velocity in handball players. Fourteen female handball players took part in the study (age: 21.2 ± 2.7 years, experience: 10.9 ± 3.5 years). For Post-Activation Potentiation, two pre-activation methods were used: (I) Variable Intra-Repetition Resistance: 1 x 5 maximum repetitions at an initial velocity of 0.6 m·s-1 and a final velocity of 0.9 m·s-1; (II) Isometry: 1 x 5 s of maximum voluntary isometric contraction. Both methods were "standing unilateral bench presses" with the dominant arm, using a functional electromechanical dynamometer. The variable analysed was the mean of the three overhead throws. Ball velocity was measured with a radar (Stalker ATS). The statistical analysis was performed using ANOVA with repeated measures. No significant differences were found for either method (variable resistance intra-repetition: p = 0.194, isometry: p = 0.596). Regarding the individual responses, the analysis showed that 86% of the sample increased throwing velocity with the variable resistance intra-repetition method, while 93% of the sample increased throwing velocity with the isometric method. Both the variable intra-repetition resistance and isometric methods show improvements in ball velocity in female handball players. However, the authors recommend checking individual responses, since the results obtained were influenced by the short rest interval between the pre-activation and the experimental sets.

Структурно-функциональные показатели сердца пациентов с ишемической болезнью сердца и сахарным диабетом 2 типа. Ритмоинотропная реакция изолированного миокарда при разном уровне гликированного гемоглобина

BACKGROUND : Adequate glycemic control can significantly reduce the risk of developing cardiovascular events. However, until now, glycaemic targets in aged patients remain a subject of discussion, especially in the conditions of the combined development of Type 2 Diabetes Mellitus (T2DM) and ischemic heart disease (IHD). AIMS : To examine the structural and functional heart parameters in patients with IHD associated with T2DM and the rhythmoinotropic responses of their isolated myocardium depending on glycated hemoglobin level. MATERIALS AND METHODS : The study included 44 patients with a diagnosis of chronic IHD associated with T2DM, of which 2 groups were formed. Patients with glycated hemoglobin level (HbA 1c ) <8% were included in the 1 st group, and patients with HbA 1c ≥8% were included in the 2 nd group. The structural and functional heart parameters obtained with ultrasonography, and the rhythmoinotropic responses of myocardium in patients ex vivo were analyzed using the right atrial appendage fragments obtained during elective coronary artery bypass graft. The inotropic response of muscle strips at a basic stimulation frequency of 0,5 Hz to testing influences was assessed. An extrasystolic test and post-rest test were performed. RESULTS : It was found that extrasystolic contractions of isolated myocardial strips in patients of the 2 nd group appeared at shorter extrasystolic intervals, which indicates a greater excitability of the myocardium in patients of this group. Postextrasystolic muscle contractions in patients of the 2 nd group had significant potentiation. The amplitude of the muscle strips contractions in patients of both groups was potentiative after short rest periods. However, with an increase in the rest duration, potentiation of contractions was observed only in the group with a higher HbA 1c level. According to the ultrasonography data, it was found that the values of the endsystolic and diastolic volumes, the interventricular septum thickness and the left ventricular (LV) myocardium mass were significantly lower in the patients of the 1 st group compared with the corresponding indicators in the patients of the 2 nd group. The early LV filling velocity (peak E) was significantly lower in the patients of the 1 st group, which indicates a slower LV relaxation. At the same time, the rapid LV filling velocity did not have a significant intergroup difference, but this indicator exceeded the reference values in both groups. CONCLUSIONS : With a moderately increased glycemic level (9,2 [8,0; 10,3]%), the structural and functional heart parameters are preserved both at the level of the isolated myocardial tissue and at the level of the whole heart.

Electrochemical Impedance Spectroscopy With Practical Rest-Times for Battery Management Applications

The State of Charge (SoC), State of Health (SoH), and State of available Power (SoaP) of Lithium-Ion Batteries (LiB) are critical quantities which cannot be measured but must be estimated by Battery Management Systems (BMS) instead. A technique known as Electrochemical Impedance Spectroscopy (EIS) provides a non-destructive way of measuring battery impedance, offering detailed insight into the battery state of operation. Several challenges must be solved in to utilize EIS as part of the BMS, including the defining of operating conditions at which to perform the sensitive EIS measurement. In laboratory conditions, several hours of rest are used to ensure a stable response of the battery, but such rest times are impractical for BMS applications. This paper proposes a methodology combining drift compensation and a Voigt-circuit used as a filter to obtain valid EIS data with short rest times under different operating conditions. Extensive tests were conducted on lithium nickel manganese cobalt (NMC) batteries to evaluate the methodology and show how the different operating conditions impact the rest time required for valid EIS measurement. The results show that rest times between 5 and 30 minutes can be used to obtain useful EIS data for a wide range of operating conditions.

INCREASING PRODUCTIVITY OF SCLUPTOR IN KAPAL VILLAGE, BADUNG, BALI

To increase the productivity, modern hand tools such as electrical grinder, electrical drill and band saw have been used by the scluptor in Kapal village. Due to ignorance, in using them not all precaution were taken into consideration. Also squatting and bending positions produced many complaints. Therefore, an ergonomics intervention has been conducted. Using multistage random sampling technique, 20 subjects were sampled from the scluptors. Blood pressure, and heart rate were measured, and subjective feelings were recorded using Nordic Body Map, before and after working for a week. The results showed that after working; 1.2% increased in systolic blood pressure; 4.7% increased HR per minute; and 20.7% subjective complaints (p&lt;0.05). To overcome the problems ergonomics intervention have been conducted which consist of three types as follows: 1) advising to have rest pause 3-5 minutes in every one hour working; 2) the workplace for electrical grinder must be separated from another workplaces, and the operator of electrical grinder machine should have a rest after 30 minutes, in case the electrical grinder could not be separated all workers there should use cotton car plugs. 3) the physical fitness of scluptors should be improved by doing exercise program 3-5 times per week. After two weeks of awareness program, responses found as follows: 87% of workers engaged in having short rest pauses 90% of workers engaged in using ear plugs and 77% were engaged fitness program. The preliminary results showed there are a decreased in systolic blood pressure 0.46%, (p&gt;0.05). HR 4.96% (p&lt;0.05), subjective complaints 18.39% (p&lt;0.05), and associated by an increased of productivity at about 17.55% (p&lt;0.05).

Effectiveness of workplace exercise interventions in the treatment of musculoskeletal disorders in office workers: a protocol of a systematic review

IntroductionPhysical inactivity due to changes in our society towards more sedentary behaviours is leading to health problems. Increasing physical activity might be a good strategy to improve physical strength and...

Contractile history affects sag and boost properties of unfused tetanic contractions in human quadriceps muscles.

A period of extra-efficient force production ("boost") followed by a decline in force ("sag") is often observed at the onset of unfused tetanic contractions. We tested the hypothesis that in human muscle boost and sag are diminished in repeated contractions separated by short rest periods and are re-established or enhanced following long rest periods. Two sets of 3 unfused tetanic contractions were evoked in the right quadriceps muscle group of 29 participants via percutaneous stimulation of the femoral nerve. Contractions consisted of 20 pulses evoked at inter-pulse intervals of 1.25 × twitch time to peak torque. Contractions were evoked 5s apart and sets were evoked 5min apart. The ratio of the angular impulse of pulses 1-10 to the angular impulse of pulses 11-20 was used as the boost indicator. By this metric, boost was higher (P < 0.05) in the first relative to the second and third contractions within a set, but did not differ between sets (Set 1: 1.31 ± 0.15, 1.18 ± 0.12, 1.14 ± 0.12 vs Set 2: 1.34 ± 0.17, 1.17 ± 0.13, 1.14 ± 0.13). Sag (the percent decline in torque within each contraction) was also higher (P < 0.05) in the first relative to the second and third contractions within a set, but did not differ between sets (Set 1: 40.8 ± 7.5%, 35.4 ± 6.8%, 33.2 ± 7.8% vs Set 2: 42.1 ± 8.0%, 35.5 ± 6.8%, 33.9 ± 7.2%). Participants' sex and resistance training background did not influence boost or sag. Boost and sag are sensitive to contractile history in whole human quadriceps. Optimizing boost may have application in strength and power sports.

Acute Physiological Responses to Ultra Short Race-Pace Training in Competitive Swimmers.

Ultra Short Race Pace training (USRPT) is an emerging training modality devised in 2011 to deviate from high-volume swimming training that is typically prescribed. USRPT aims to replicate the exact demands of racing, through its unique prescription of race-pace velocity sets with short rest intervals. It has been surmised, with little physiological evidence, that USRPT provides swimmers with the best opportunity to optimize the conditioning, technique, and psychology aspects of racing at the most specific velocity of the relevant event, with low blood lactate concentration. The aim of this study was to examine acute physiological responses of USRPT. Fourteen swimmers were recruited to perform a USRPT set: 20 x 25 m freestyle with a 35-s rest interval. Swimmers were required to maintain the velocity of their 100 m personal best time for each sprint. Sprint performance, blood lactate, heart rate and the RPE were measured. Blood lactate was taken before, during (after every 4 sprints) and 3 minutes after the USRPT protocol. Heart rate monitors were used to profile the heart rate. Athletes reported the RPE before- and after completion of the USRPT set. Sprint times increased by 3.3-10.8% when compared to the first sprint (p < 0.01). There was high blood lactate concentration (13.6 ± 3.1mmol/l), a significant change in the RPE from 8 ± 1.6 to 18 ± 1.6 (p < 0.01) and a substantially high heart rate profile with an average HRmax of 188 ± 9 BPM. The results show the maximal intensity nature of USRPT and portray it as an anaerobic style of training.

Utility of a Shortened Isometric Midthigh Pull Protocol for Assessing Rapid Force Production in Athletes.

Suarez, DG, Carroll, KM, Slaton, JA, Rochau, KG, Davis, MW, and Stone, MH. Utility of a shortened isometric midthigh pull protocol for assessing rapid force production in athletes. J Strength Cond Res 36(7): 1819-1825, 2022-The purpose of this investigation was to determine the magnitude of difference, reliability, and relationship to performance of a shortened isometric midthigh pull (IMTP) protocol. Fourteen strength-trained men (age: 26.8 ± 5.0 years, height: 176.3 ± 6.9 cm, body mass: 86.8 ± 13.9 kg, and training age: 8.5 ± 6.9 years) performed 1-second (SHORT) and traditional (TRAD) IMTP protocols during consecutive weeks. Peak force (PF), instantaneous force (90 & 200 ms), rate of force development (RFD) (0-90 ms & 0-200 ms), and impulse (0-90 ms & 0-200 ms) from each protocol were collected. Paired samples t test and Hedge's g were calculated to determine the magnitude of difference in each variable between protocols. Within-session and between-session reliability was assessed with intraclass correlation coefficient, coefficient of variation, and 95% confidence intervals. Static jumps were performed to compare relationships of the IMTP variables from each protocol with jumping performance. There was no statistically significant (p > 0.05) difference in PF between the protocols (p = 0.345; g = -0.07). All early force-time variables were significantly higher in the SHORT protocol (p = <0.001-0.018; g = 0.38-0.79). The SHORT protocol resulted in more reliable RFD measures within-session. Correlations with jumping performance were mostly similar between protocols (r = 0.253-0.660). The SHORT IMTP protocol resulted in comparable PF values and considerably higher early force-time characteristics despite a restrained time to produce force and shorter rest. The SHORT protocol allows for an accurate assessment of rapid force-generating abilities while necessitating shorter collection periods than typical IMTP protocols.

A fast capacity estimation method based on open circuit voltage estimation for LiNixCoyMn1-x-y battery assessing in electric vehicles

Abstract With the widespread popularity of electric vehicles (EV), effective assessment for retired EVs has become increasingly critical. Unlike traditional internal combustion vehicles, for EV, batteries account for a large proportion of the entire vehicle cost. Therefore, a fast battery capacity estimation method based on open-circuit voltage (OCV) estimation is forthwith proposed. The method calculates capacity using the ratio of the change in electric quantity to the corresponding change in state-of-charge (SOC), and the SOC is estimated via a fast OCV estimation method proposed in this paper. The fast test procedure includes a charging/discharging test and a short rest, which take less than 30 minutes in total and provide the data for the battery capacity estimation. For estimation, a weighted voltage relaxation model, containing two parallel resistor–capacitor (RC) components, is established. Its parameters are then optimized using the beetle antenna search algorithm with the approximate OCV range obtained in the test and an early voltage relaxation curve. The results of the experiments show that the proposed model and algorithm can accurately estimate the OCV, and the capacity estimation can be quickly realized in half an hour while limiting inaccuracy to less than 3%.

Abstract P154: Results From A Randomized Trial Of Different Rest Times Before Initiating BP Measurements

Background: BP measurement guidelines recommend ≥5 min of rest before initiation of readings; this wait time is challenging to implement, especially in resource-constrained settings. Objective: Compare the effects of resting 0 or 2 min vs. 5 min on BP. Design and methods: RCT of community-dwelling adults, 18-80yrs. Participants had 4 sets of BP measurements (Omron HEM 970XL). In a cross-over design, the order of rest for the 1 st 3 sets [0min, 2min, 5min 1 ] was random. The 4 th set was always a 2nd 5min rest period (5min 2 ) to estimate repeatability. Mean BP for each rest period, mean absolute difference between each participant’s mean BP after 5min 1 and the other rest periods were determined. To determine if resting 0min and/or 2min was non-inferior to 5min 1 , we calculated the difference of differences, with ≤ ±2 mmHg considered non-inferior. Analyses were for the population overall and stratified by SBP ≥ vs. &lt; 140mmHg. Results: N=113, mean age 55yrs, 36% male (n=41), 74% AA (n=84), 28% SBP &gt; 140mmHg (n=32). Overall, mean 5min 1 BP was 128/75 and 5min 2 BP was 127/76 (p=NS), similar to mean BP at 2min and 0min (127/74 for both). The absolute difference of differences between 2min and 5min 1 SBP for the population overall was &gt; ±2 mmHg, but for those with SBP &lt;140, resting 2min and 0min BP was ≤ ±2 mmHg (Table). Conclusion: In this RCT, mean differences in BP by rest period were small. BPs obtained after shorter rest periods were non-inferior than those obtained after 5min when SBP &lt;140. This suggests shorter rest times, even 0 min, may be reasonable for screening when the initial SBP is &lt;140. These findings could improve the efficiency of hypertension screening, especially in resource-constrained settings.

Climbing Waterfalls: How Metabolism and Behavior Impact Locomotor Performance of Tropical Climbing Gobies on Reunion Island.

The life cycle of gobies of the Sicydiinae subfamily depends on climbing waterfalls. Two sympatric sicydiines species from Reunion Island, Sicyopterus lagocephalus (SIL) and Cotylopus acutipinnis (COA), employ different climbing modes. SIL uses a steady "inching" mode interrupted by short rest periods, whereas COA exhibits short "power-burst" undulatory movements punctuated by longer rest periods. Consequently, we explored the relationship between climbing performance and metabolic activity in these two species. We demonstrated that the two climbing modes are supported by different ecophysiological profiles that promote the interspecific variability of locomotor performance. More specifically, SIL performed better than COA during a climbing experiment because of its inching climbing mode, supported by a generally greater metabolic capacity and a higher potential for oxidative metabolism. Interestingly, we did not detect any difference in metabolic fuel storage and lactate production during climbing in either species, suggesting that these species can maintain fuel reserves and limit lactate accumulation through extensive rest times. Overall, this study provides new insights into the ecophysiology of these two emblematic species and suggests that the better climbing capacity of SIL is supported by its muscular metabolic capacity.

Effect of three different Pilates sessions on energy expenditure and aerobic metabolism in healthy females

The Pilates method has become a popular exercise modality. However, there is little information on the energy expenditure (EE) and aerobic metabolism involved in a Pilates session. This study aimed to compare the EE of three different types of Pilates sessions. Thirty-three sedentary women (22.03 ± 3.32 years old) performed three Pilates sessions: (1) a traditional session (TS): single set, low volume of repetitions, and long rest interval; (2) non-traditional session (NSS): single set, a high volume of repetitions, and short rest interval; and (3) non-traditional session (NMS): multiple sets and short rest interval. In each session, EE per minute (EE/min), total EE (TEE), oxygen consumption (V’O2), respiratory exchange ratio (RER), and metabolic equivalent were determined via a gas analyzer. Heart rate (HR) was measured via a HR monitor. Repeated measures two-way ANOVA (time × session) followed by Tukey test were used to compare differences in each variable for the sessions (P ≤ 0.05). When compared to the TS session, the non-traditional sessions resulted in greater EE/min, TEE, V’O2, RER, and mean HR (P < 0.001). TEE in NMS was also greater than NSS (P < 0.001). Our findings indicate that a non-traditional approach to Pilates, with multiple sets, high repetitions, and a shorter rest interval induces greater metabolic cost than a traditional Pilates session. However, the total caloric cost of high-volume protocols such as the NMS performed in this study is small compared to aerobic exercise and does not contribute significantly to daily EE.

Intra-session and inter-rater reliability of spatial frequency analysis methods in skeletal muscle.

Spatial frequency analysis (SFA) is a quantitative ultrasound (US) method originally developed to assess intratendinous tissue structure. This method may also be advantageous in assessing other musculoskeletal tissues. Although SFA has been shown to be a reliable assessment strategy in tendon tissue, its reliability in muscle has not been investigated. The purpose of this study was to examine the reliability of spatial frequency parameter measurement for a large muscle group within a healthy population. Ten participants with no history of lower extremity surgery or hamstring strain injury volunteered. Longitudinal B-mode images were collected in three different locations across the hamstring muscles. Following a short rest, the entire imaging procedure was repeated. B-mode images were processed by manually drawing a region of interest (ROI) about the entire muscle thickness. Four spatial frequency parameters of interest were extracted from the image ROIs. Intra- and inter-rater reliabilities of extracted SFA parameters were performed. Test-retest reliability of the image acquisition procedure was assessed between repeat trials. Intraclass correlation coefficients showed high intra- and inter-rater reliability (ICC(3,1) > 0.9 for all parameters) and good to moderate test-retest reliability (ICC(3,1) > 0.50) between trials. No differences in parameter values were observed between trials across all muscles and locations (p > 0.05). The high reliability metrics suggest that SFA will be useful for future studies assessing muscle tissue structure, and may have value in assessing muscular adaptations following injury and during recovery.

Volume Load Rather Than Resting Interval Influences Muscle Hypertrophy During High-Intensity Resistance Training.

Longo, AR, Silva-Batista, C, Pedroso, K, de Salles Painelli, V, Lasevicius, T, Schoenfeld, BJ, Aihara, AY, de Almeida Peres, B, Tricoli, V, and Teixeira, EL. Volume load rather than resting interval influences muscle hypertrophy during high-intensity resistance training. J Strength Cond Res 36(6): 1554-1559, 2022-Interset rest interval has been proposed as an important variable for inducing muscle mass and strength increases during resistance training. However, its influence remains unclear, especially when protocols with differing intervals have equalized volume. We aimed to compare the effects of long (LI) vs. short rest interval (SI) on muscle strength (one repetition maximum [1RM]) and quadriceps cross-sectional area (QCSA), with or without equalized volume load (VL). Twenty-eight subjects trained twice a week for 10 weeks. Each subject's leg was allocated to 1 of 4 unilateral knee extension protocols: LI, SI, SI with VL -matched by LI (VLI-SI), and LI with VL-matched by SI (VSI-LI). A 3-minute rest interval was afforded in LI and VSI-LI protocols, while SI and VLI-SI employed a 1-minute interval. All subjects trained with a load corresponding to 80% 1RM. One repetition maximum and QCSA were measured before and after training. All protocols significantly increased 1RM values in post-training (p < 0.0001; LI: 27.6%, effect size [ES] = 0.90; VLI-SI: 31.1%, ES = 1.00; SI: 26.5%, ES = 1.11; and VSI-LI: 31.2%, ES = 1.28), with no significant differences between protocols. Quadriceps cross-sectional area increased significantly for all protocols in post-training (p < 0.0001). However, absolute changes in QCSA were significantly greater in LI and VLI-SI (13.1%, ES: 0.66 and 12.9%, ES: 0.63) than SI and VSI-LI (6.8%, ES: 0.38 and 6.6%, ES: 0.37) (both comparisons, p < 0.05). These data suggest that maintenance of high loads is more important for strength increases, while a greater VL plays a primary role for hypertrophy, regardless of interset rest interval.

Initial force production before sag is enhanced by prior contraction followed by a 3-minute rest period in fast motor units of the rat medial gastrocnemius

Unfused tetanic contractions evoked in fast motor units exhibit extra-efficient force production at the onset of contraction, an effect called “boost”. Boost is diminished in subsequent contractions if there is a short rest period between contractions, but can be re-established with a longer period of rest. We tested the hypothesis that contractile activity and rest could enhance boost-related metrics. Two sets of 3 unfused tetani were evoked 3 min apart in fast fatigable (FF) and fast fatigue-resistant (FR) motor units of the rat medial gastrocnemius. The greatest changes occurred in the first unfused tetanic contractions. Relative to the first contraction in the first set, the first contraction in the second set exhibited higher peak force during boost in a subset of motor units (76% of FF and 48% of FR). Enhanced force during boost was influenced by interaction of slowing of twitch contraction time (up to 20% and 25%, for FF and FR motor units, respectively), half-relaxation time (up to 37% and 49% for FF and FR motor units, respectively), and potentiation of the first twitch (up to 13% and 5% for FF and FR motor units, respectively). Examination of twitches evoked between sets suggested opportunity for greater enhancement of boost with shorter intervening rest periods. The phenomenon of enhanced boost following motor unit activity may interest sports scientists.

The Effect of Thursday Night Games on In-Game Injury Rates in the National Football League

Background: Although claims of increased injury rates with Thursday night National Football League (NFL) games exist, a paucity of data exist substantiating these claims. Purpose: To evaluate the effect of rest between games on in-game injury rates as it pertains to overall injury incidence, location, and player position. Study Design: Descriptive epidemiologic study. Methods: Data were obtained from official NFL game books for regular season games from all 32 teams for the 2013-2016 seasons. All in-game injuries recorded in official game books were included. Rest periods between games were classified as short (4 days), regular (6-8 days), or long (≥10 days). Overall observed injury rates per team-game were analyzed in relation to different rest periods using negative binomial regression. For results with significant overall findings, pairwise comparisons were tested using the Wald chi-square test. Exploratory secondary analyses were performed in a similar fashion to assess differences in injury rates for the different rest periods when stratified by anatomic location and player position. Results: A total of 2846 injuries were identified throughout the 4 seasons. There was an overall significant difference in injuries per team-game between short, regular, and long rest (P = .01). With short rest, an observed mean of 1.26 injuries per game (95% CI, 1.06-1.49) was significantly different from the 1.53 observed injuries per game with regular rest (95% CI, 1.46-1.60; P = .03), but not compared with the 1.34 observed injuries per game with long rest (P = .56). For player position, only the tight end, linebacker, and fullback group demonstrated significant differences between the injury rates for different rest categories. Quarterback was the only position with more injuries during games played on Thursday compared with both regular and long rest. This specific analysis was underpowered and the difference was not significant (P = .08). No differences were found regarding injury rates in correlation with differences in rest periods with different injury locations. Conclusion: A short rest period between games is not associated with increased rates of observed injuries reported in NFL game books; rather, our data suggest there are significantly fewer injuries for Thursday night games compared with games played on regular rest. Future research correlating rest and quarterback injury rates is warranted.