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Influence of muscle temperature on maximal muscle strength and power output in human skeletal muscle
Abstract
The influence of muscle temperature (Tm) on maximal muscle strength, power output, jumping, and sprinting performance was evaluated in four male subjects. In one of the subjects the electromyogram (EMG) was recorded from M. vastus lateralis, M. biceps femoris, and M. semitendinosus. Tm ranged from 30.0 degrees C to 39 degrees C. Maximal dynamic strength, power output, jumping, and sprinting performance were positively related to Tm. The changes were in the same order of magnitude for all these parameters (4-6% x degrees C-1) Maximal isometric strength decreased by 2% x degrees C-1 with decreasing Tm. The force-velocity relationship was shifted to the left at subnormal Tm. Thus in short term exercises, such as jumping and sprinting, performance is reduced at low Tm and enhanced at Tm above normal, primarily as a result of a variation in maximal dynamic strength.
... However, beyond 20 min, it has been shown that any benefit of a warm-up is lost in swimmers, which is associated with a loss in body temperature prior to the start of competition [19]. This is due to the fact that the muscle temperature needs to be maintained, otherwise a rapid decrease in the muscle temperature can also occur upon the cessation of exercise [20,21], and this decreased muscle temperature has been shown to reduce exercise performance in temperate environments [22]. ...
... There were 10 participants (5 females) in the CON condition that increased MVC, on average by 38.9 N, whereas in the 12IP, there was an average decrease of 22.7 N for 8 participants (4 females). The reduced MVC in the 12IP condition may be explained by greater cooling affecting the muscle temperature, which can reduce muscle power [11,22] and peak power by up to 7.2% at −14 • C [23]. Given that the 12IP condition did not have a significantly lower core body temperature compared to CON and 6IP, this points to muscle tissue temperature potentially being the more important factor in muscle power decline. ...
... Given that the 12IP condition did not have a significantly lower core body temperature compared to CON and 6IP, this points to muscle tissue temperature potentially being the more important factor in muscle power decline. This is in contrast to previous research, which showed that the core temperature and muscle tissue temperature fall in parallel with reduced muscle power immediately after cooling has occurred in the leg muscle [22]. We would hypothesize that the warm-up with the slow walking that occurred in the interim period might have been sufficient to maintain the core temperature but not sufficient to maintain the muscle tissue temperature; however, more research should explore this hypothesis. ...
We investigated the influence of different-length interim periods after a standardized warm-up on the physiological, perceptual and performance responses in males and females. Fourteen participants (eight females, six males; age: 24.7 ± 5.6 years; V̇O2max 54.6 ± 5.5 mL/kg/min) completed three environmental chamber trials [0 (CON), 6 (6IP) or 12 (12IP)-minute interim period] preceded by the same 15 min warm-up and followed by a subsequent 8-min running performance trial at −15.0 °C. The maximal knee extension force, heart rate, muscle oxygenation, thermal state, cold discomfort and perceived leg discomfort were measured. The distance run was the same between conditions but the average (p = 0.008) and peak heart rates (p = 0.034), as well as the thermal state (p < 0.001), were all greater in the CON compared to 12IP. Females did have heavier legs and felt colder at the end of the interim periods, with continued heavier legs and cold discomfort across the performance trial, although these increases were not significant (p > 0.05). Thus, increasing the rest time in severe cold alters physiological and perceptual responses, especially in females, but does not influence running performance over 8-min. It is recommended that minimizing wait times will reduce the effects of severe cold air cooling before an outdoor winter sport competition.
... As a result, regression models for the prediction of strength from anthropometric variables have been proposed [19]. These values, coupled with the properties of the subject body are what the biomechanical model is based on, for example, sex [20], age [20][21][22][23], body mass [20,24,25], body height [20,24,26], dominant side [21,27], physical activity [28], skin temperature [29][30][31][32][33], impact strength of muscles, anatomical locations, the center of mass (COM), and inertia parameters [34,35]. ...
... A mean value supplied by [63] for training time per week is represented by ς and is equal to 0.065. According to Ekblom and Bergh [32], the peak muscle torque increases 3% for each skin temperature more than 20 o , no more than 40 o . We used arctan instead of simple slope to limit the maximum of impact of skin temperature. ...
... When determining the maximum isometric moment-generating capability, we consider the model's maximum activation for MTG. As mentioned in section 3.2, the peak isometric torque at the joints is influenced by various factors, including age [20,22,23], height [20,24,26], body mass [20,24,25], as well as sex, dominant side [27], athletic activity [63], and skin temperature [32]. ...
A musculoskeletal (MSK) model is an important tool for analysing human motions , calculating joint torques during movement, enhancing sports activity, and developing exoskeletons and prostheses. To enable biomechanical investigation of human motion, this work presents an open-source lower body MSK model. The MSK model of the lower body consists of 7 body segments (pelvis, left/right thigh, left/right leg, and left/right foot). The model has 20 degrees of freedom and 28 muscle torque generators, which are developed from experimental data. The model can be modified for different anthropometric measurements and subject body characteristics, including sex, age, body mass, height, physical activity, and skin temperature. The model is validated by simulating the torque within the range of motion of isolated movements; all simulation findings exhibit a good level of agreement with the literature.
... While CWI improves the performance of intermittent and endurance exercises performed in warm environments (Marino 2002;Wegmann et al. 2012;Ross et al. 2013;Tyler et al. 2013;Ihsan et al. 2016), its effectiveness prior to anaerobic exercise remains controversial (Tyler et al. 2013;Versey et al. 2013). Different studies have reported an increase (Marsh and Sleivert 1999), maintenance (Peiffer et al. 2010), or even a decrease (Bergh and Ekblom 1979;Sargeant 1987;Ferretti et al. 1992;Schniepp et al. 2002) of anaerobic mechanical power after CWI. Thus, while post-exercise CWI may be beneficial from a physiological point of view in terms of accelerating blood [La − ] recovery, it may be detrimental to subsequent anaerobic performance. ...
... The deterioration of physical performance due to adverse environmental conditions, such as when the athlete feels cold or wet (pre-immersion), has been observed in other studies, especially during exercises executed at high intensity (Bergh and Ekblom 1979;Howard et al. 1994;Schniepp et al. 2002). Contrary to these results, Marsh and Sleivert (1999) found an increase in power after performing pre-immersion for 30 min at a temperature between 12 and 18 ℃. ...
... The authors highlighted that in high-speed situations, a slight alteration in the agonist/antagonist balance can impair the coordination of movements and hinder an adequate production of force. Bergh and Ekblom (1979), on the other hand, did not find alterations in the EMG signal during exercise in cycloergometer after muscular cooling from 38 to 30 ℃; however, they verified a decrease of 4-6% in the power produced for each 1 ℃ of reduction in the muscular temperature. In this sense, muscle cooling seems to impair performance, especially at high velocities of muscle contraction ) by reducing pedaling frequency. ...
Purpose:
While exercise recovery may be beneficial from a physiological point of view, it may be detrimental to subsequent anaerobic performance. To investigate the energetic responses of water immersion at different temperatures during post-exercise recovery and its consequences on subsequent anaerobic performance, a randomized and controlled crossover experimental design was performed with 21 trained cyclists.
Method:
Participants were assigned to receive three passive recovery strategies during 10 min after a Wingate Anaerobic Test (WAnT): control (CON: non-immersed condition), cold water immersion (CWI: 20 ℃), and hot water immersion (HWI: 40 ℃). Blood lactate, cardiorespiratory, and mechanical outcomes were measured during the WAnT and its recovery. Time constant (τ), asymptotic value, and area under the curve (AUC) were quantified for each physiologic parameter during recovery. After that, a second WAnT test and 10-min recovery were realized in the same session.
Results:
Regardless the water immersion temperature, water immersion increased [Formula: see text] (+ 18%), asymptote ([Formula: see text]+ 16%, [Formula: see text] + 13%, [Formula: see text] + 17%, HR + 16%) and AUC ([Formula: see text]+ 27%, [Formula: see text] + 18%, [Formula: see text] + 20%, HR + 25%), while decreased [Formula: see text] (- 33%). There was no influence of water immersion on blood lactate parameters. HWI improved the mean power output during the second WAnT (2.2%), while the CWI decreased 2.4% (P < 0.01).
Conclusion:
Independent of temperature, water immersion enhanced aerobic energy recovery without modifying blood lactate recovery. However, subsequent anaerobic performance was increased only during HWI and decreased during CWI. Despite higher than in other studies, 20 °C effectively triggered physiological and performance responses. Water immersion-induced physiological changes did not predict subsequent anaerobic performance.
... It was hypothesized that a standardized dynamic warm-up period, including low-intensity, nonspecific exercises progressing to maximal specific exercises, would have greater beneficial effects on short-term high-intensity exercise performance (i.e., vertical jump performance) in postpubertal than in prepubertal male youngsters. These benefits in postpubertal athletes could be greater during the SJ than during drop jump (DJ) because changes in muscle power during the SJ should theoretically result from increases in muscle temperature (8) whereas the DJ performance, which requires a stretchshortening cycle (SSC) and coordination ability, could be too complex to be influenced by a simple standardized dynamic warm-up. ...
... Vertical jump outcomes obtained before warm-up and across the different post-warm-up time points (mean 6 SD).* 16), who showed an increased CMJ height following dynamic exercises as compared with static stretch exercises up to 6 minutes after the completion of the intervention in 16.5-year-old male adolescents. The 12.0% improvement in SJ height up to 3 minutes after warm-up could be explained by the increase in muscle temperature (8), which seems to be a main cause for the increase in short duration performance (11) because it allows for an increase in muscle power (9,31). The improvement in SJ performance in the first 3 minutes might also be ascribed to an increase in muscle or cellular water content, which affects the contractile response (i.e., actin-myosin cross-bridge cycle) and may have a similar time course to increases in muscle temperature (12). ...
... In addition, the athletes' strength training backgrounds and strength levels should not represent important variables in PAPE because (a) some previous studies showed no differences in PAPE after a conditioning activity between power track and field athletes (training for power), bodybuilders (training for hypertrophy), and physically active (no strength training experience) adult subjects (5), (b) metaanalysis revealed no clear effects (nonoverlap in 95% confidence intervals) between cohorts with different training backgrounds or strength levels (32), and (c) significant correlations were not observed between strength and jumping performance before and after a conditioning activity in strength-trained adult individuals (22). Another possible limitation is that muscle temperature was not measured in this study, yet it is considered as one of the main factors accounting for power output (8), notably in fast-twitch fibers at high muscle contraction velocities (17). ...
Ferrari, A, Baquet, G, Blazevich, AJ, and Ratel, S. Influence of recovery time after warm-up on vertical jump performance in trained prepubertal and postpubertal male athletes. J Strength Cond Res XX(X): 000-000, 2023-The aim of this study was to examine the concurrent effects of maturity status and recovery delay after a standardized dynamic warm-up on vertical jump performance. Thirteen prepubertal boys (9.4 ± 1.1 years) and 12 postpubertal boys (16.6 ± 0.8 years) were tested on squat jump (SJ) and drop jump from 30 cm (DJ30) before and after a standardized, 8-minute, dynamic warm-up, including low-intensity, nonspecific dynamic exercises progressing to maximal, specific exercises, over 6 separate occasions. In each session, subjects jumped at 0, 1.5, 3, 5, 7, or 10 minutes after warm-up in a randomized order. Measurements included SJ height, DJ30 height, ground contact time (GCT), and reactive strength index (RSI) from DJ30. The results revealed no significant recovery time × maturity group interaction effects for SJ height (p = 0.36), DJ30 height (p = 0.45), GCT (p = 0.75), or RSI (p = 0.09), meaning that maturity status did not have a significant effect on changes in vertical jump performance after the warm-up. However, there were significant time effects for SJ height, DJ30 height, and RSI (p < 0.001 for all), with DJ30 height and RSI increasing significantly by 16.9% at 1.5 minutes (p < 0.001) and SJ height increasing significantly by 12.0% until 3 minutes after the warm-up (p < 0.001). To conclude, the standardized dynamic warm-up had beneficial effects on vertical jump performance within the first 3 minutes after completion of the intervention. However, vertical jump performance after the warm-up was not dependent on the children's maturity status.
... Severe muscle cooling also elicits a shift towards a slower muscle contractile profile (Davies et al., 1982;de Ruiter et al., 1999), while it could limit force decline during repeated contractions induced by electrical stimulation (Davies et al., 1982). In contrast, moderate muscle cooling, that can be defined as a reduced temperature up to 5°C in the deep portion of the muscle, does not (Petrofsky and Phillips, 1986) or only slightly (Asmussen et al., 1976;Bergh and Ekblom, 1979;Brazaitis et al., 2011) reduces MVIC force. Some evidence indicates that it reduces force during dynamic voluntary contractions, at least of the knee extensors (Bergh and Ekblom, 1979), and force response to 50 Hz electrical stimulations . ...
... In contrast, moderate muscle cooling, that can be defined as a reduced temperature up to 5°C in the deep portion of the muscle, does not (Petrofsky and Phillips, 1986) or only slightly (Asmussen et al., 1976;Bergh and Ekblom, 1979;Brazaitis et al., 2011) reduces MVIC force. Some evidence indicates that it reduces force during dynamic voluntary contractions, at least of the knee extensors (Bergh and Ekblom, 1979), and force response to 50 Hz electrical stimulations . However, it may not affect the drop in force (i.e., fatigue resistance) and half relaxation time (HRT) during repeated electrical stimulations induced contractions . ...
... Human studies evaluating the impact of local cooling on muscle force and contractile properties generally include one single CWI where the immersion time is either not documented [but adjusted so that skeletal muscle reaches a certain temperature (Asmussen et al., 1976;Bergh and Ekblom, 1979)] or limited to a duration <45 min (Davies et al., 1982;de Ruiter et al., 1999;Brazaitis et al., 2011;Brazaitis et al., 2012). To investigate physiological changes in response to prolonged muscle cooling (i.e., several hours), intermittent water immersions can be used to limit cold sensation (Castellani et al., 1998). ...
Background: We investigated the impact of moderate muscle cooling induced by single and intermittent/prolonged cold-water immersions (CWI) on muscle force and contractility in unfatigued state and during the development of fatigue resulting from electrically induced contractions.
Methods: Twelve young males participated in this study consisting of two phases [single phase (SP) followed by intermittent/prolonged phase (IPP)], with both phases including two conditions (i.e., four trials in total) performed randomly: control passive sitting (CON) and cold-water immersions (10°C). SP-CWI included one 45 min-bath (from 15 to 60 min). IPP-CWI included three baths (45 min-bath from 15 to 60 min, and 15 min-baths from 165 to 180 min and from 255 to 270 min), with participants sitting at room temperature the rest of the time until 300 min. Blood pressure and intramuscular (Tmu) temperature were assessed, and neuromuscular testing was performed at baseline and 60 min after baseline during SP, and at baseline, 60, 90, 150 and 300 min after baseline during IPP. A fatiguing protocol (100 electrical stimulations) was performed after the last neuromuscular testing of each trial.
Results: In unfatigued state, SP-CWI and IPP-CWI reduced electrically induced torque at 100 Hz (P100) but not at 20 Hz (P20), and increased P20/P100 ratio. The changes from baseline for P100 and P20/P100 ratio were lower in IPP-CWI than SP-CWI. Both cold-water immersion conditions slowed down muscle contraction and relaxation, and reduced maximal isokinetic contraction torque, but the changes from baseline were lower after IPP-CWI than SP-CWI. cold-water immersions did not impair maximal voluntary isometric contraction. During the fatiguing protocol, torque fatigue index and the changes in muscle contractile properties were larger after IPP-CWI than SP-CWI, but were in the same range as after CON conditions. The differences of muscle contractile function between SP-CWI and IPP-CWI were accompanied by a lower reduction of superficial Tmu and a smaller increase in systolic blood pressure after IPP-CWI than SP-CWI.
Conclusion: IPP-CWI induces a less pronounced fast-to-slow contractile transition compared to SP-CWI, and this may result from the reduced vasoconstriction response and enhanced blood perfusion of the superficial muscle vessels, which could ultimately limit the reduction of superficial Tmu.
... In practical application, an athlete's velocity will not be constrained following cold-water immersion, thus changes in running mechanics as a result of cryotherapy may be related to decreased velocity. In addition, cold water immersion has been shown to decrease concentric muscle strength (27) and decrease muscular power after a muscle has been cooled (2,4,18). Cryotherapy has also been associated with decreases in task performance, which was further exacerbated when the task was performed at a higher velocity (19,22). ...
... As plantarflexor power provides propulsion during late stance, decreases in this measure are coupled with decreases in running velocity, and may therefore indicate performance decrements. This decrease in propulsive power, along with decreases in concentric muscle strength (27) and decreased muscular power (2,4,18) occurred in previous cryotherapy research studies, supporting the notion that overall performance may be influenced by the use of cryotherapy. Similar effects were observed in a study which demonstrated that a 20-minute lower extremity whirlpool treatment (10 °C) led to increased 40yard dash times, decreased countermovement vertical jump height, and decreased ankle dorsiflexion (20). ...
... Local cold application on the skin is a common practice in sports medicine, and rehabilitation is known for its neuromuscular benefits (Lu et al. 2021;Metcalfe and Nigel 1998;Nam and Park 2022;Partridge et al. 2021;Wu et al. 2021). These benefits primarily include motor facilitation and reduction of spasticity (Bawa et al. 1983;Bergh and Ekblom 1979;Christensen and Mohamed 1984;Clendenin and Szumski 1971;Fruth and Michlovitz 2016;Knutsson and Lu et al. 2021;Mattsson 1969;Metcalfe and Nigel 1998;Torres et al. 2017;Urbscheit and Bishop 1970). However, the effects of cold application on motor function can vary depending on factors such as application time, cooling agent (iced water, cooling spray, etc.), and subcutaneous fatty tissue thickness (Fruth and Michlovitz 2016). ...
... However, the effects of cold application on motor function can vary depending on factors such as application time, cooling agent (iced water, cooling spray, etc.), and subcutaneous fatty tissue thickness (Fruth and Michlovitz 2016). Prolonged and intense cooling can decrease muscle temperature to subnormal levels, resulting in gamma motor neuron inhibition, muscle spindle inhibition, muscle conduction block, and decreased motor performance (Bergh and Ekblom 1979;Christensen and Mohamed 1984;Fruth and Michlovitz 2016;Lu et al. 2021;Torres et al. 2017;Urbscheit and Bishop 1970). On the other hand, brief cooling to reduce skin temperature has been observed to induce motor facilitation (Bawa et al. 1983;Christensen and Mohamed 1984;Clendenin and Szumski 1971;Fruth and Michlovitz 2016;Knutsson and Mattsson 1969;Lu et al. 2021;Roatta et al. 2008;Urbscheit and Bishop 1970). ...
Background
Although brief skin cooling (BSC) is widely used in sports medicine and rehabilitation for its positive effects on motor performance, the mechanism underlying this motor facilitation effect remains unclear.
Objectives
To explore the hypothesis that BSC enhances muscle force generation, with cold-induced sympathetic activation leading to heightened muscle spindle sensitivity, thereby contributing to this effect.
Methods
The study involved two experiments. Experiment 1 included 14 healthy volunteers. Participants submerged their hand in ice water for 3 min. Sympathetic activity was measured via heart rate (HR), muscle force generation was assessed through plantar flexor strength during maximum voluntary contraction (MVC), and cortical contribution to force generation via the volitional wave (V-wave) with and without the cold pressor test (CPT). Experiment-2 involved 11 healthy volunteers and focused on muscle spindle sensitivity and Ia synapse efficacy, assessed using soleus T-reflex and H-reflex recordings before, during, and after CPT.
Results
Experiment 1 showed significant increases in HR (7.8%), MVC force (14.1%), and V-wave amplitude (93.4%) during CPT compared to pre-CPT values (p = 0.001, p = 0.03, and p = 0.001, respectively). In Experiment-2, hand skin temperature significantly decreased during CPT and remained lower than pre-CPT after 15 min (p < 0.001). While H-reflex and background EMG amplitudes remained unchanged, T-reflex amplitude (113.7%) increased significantly during CPT and returned to pre-CPT values immediately afterward (p < 0.001). A strong correlation was also observed between HR and T-reflex amplitude (r = 0.916, p = 0.001).
Conclusion
BSC enhances muscle spindle sensitivity via the sympathetic nervous system, promoting more significant muscle force generation. The method used in this study can be safely applied in clinical practice.
Graphic abstract
... Though not all studies agree, substantial literature exists showing application of cold directly to an exercising region of muscle acutely reduces maximal strength (Bergh & Ekblom, 1979;Grose, 1958;Holewijn & Heus, 1992;Johnson & Leider, 1977;Kwon et al., 2013), while also exerting an important anti-fatigue effect (Bacon et al., 2012;Clarke et al., 1958;Edwards et al., 1972;Galoza et al., 2011;Holewijn & Heus, 1992;Kwon et al., 2013;Lind, 1959;Verducci, 2000). For example, early studies report ~11-to-21% decrease in maximal strength following limb cold water immersion (10-15°C for 8-30 min) (Grose, 1958;Johnson & Leider, 1977) whereas application of ice or cold packs to exercising muscle has been shown to increase the volume of work completed by ~15-26% (Bacon et al., 2012;Galoza et al., 2011;Thornley et al., 2003;Verducci, 2000). ...
... Based on studies that demonstrate cold-induced reductions in strength, it is estimated that maximal strength declines ~3% per 1°C decrease in muscle temperature (Bergh & Ekblom, 1979;Holewijn & Heus, 1992;Sargeant, 1987). Interestingly, one of the original investigations on local cold exposure noted an immediate decrease in maximal strength that persisted until ~40 min postexercise and then increased ~20% above pretreatment levels; demonstrating the importance of timing (Johnson & Leider, 1977). ...
The purpose of this study was to explore the effects of local heating and cooling with isometric exercise training of upper arm and forearm. College-aged (n=12; 21±1 y) volunteers performed 4-wk isometric exercise training of the non-dominant arm (upper arm, isometric bicep curl; forearm, handgrip), while the dominant arm served as the control. Training was performed 3x/wk and consisted of 1 set of isometric handgrip and bicep curl until volitional exhaustion at 60% pre-training MVC for the forearm (handgrip) and 1RM for the upper arm (bicep curl). Randomized ordering of heating (40°C; 15 min) and cooling (12°C; 15 min) preceded each training session. Indirect assessment of muscle size (fat-free cross-sectional area [FFCSA]) was made before and after the training period via skin fold and limb circumference measures. Biceps 1RM increased significantly (p < 0.05) after the intervention in both conditions (trained: +6%; control: +7%), whereas only the control arm increased time to fatigue (+40%; p < 0.05). FFSCA of the upper arm remained unchanged (p>0.05) in both conditions. An effect of time was noted for forearm MVC (+8%; p < 0.05), while both groups increased (p < 0.05) time to fatigue (trained: +82%; control: +64%). A trend toward an effect of time was also noted for FFCSA of the forearm (+3%; p <.10). While the intervention employed here led to many notable adaptations, the thermal stress did not appear to exert a clear benefit. Coupled with the practicality and feasibility, improving size and performance in such a short time frame has therapeutic and ergogenic aid implications.
... The current analysis also shows that power (i.e., sprint and jump) performances are impaired in the short-term following CWI (Figure 3a). These findings are largely anticipated, given established work demonstrating slowed rate of force development during both voluntary and electrically evoked contractions following lowered tissue temperatures (Bergh & Ekblom, 1979;De Ruiter et al., 1999;Sargeant, 1987). Practitioners must therefore exercise caution and ensure appropriate warm-up and rewarming if the use of CWI is warranted between closely scheduled performances. ...
... This perhaps implies that maximal force production is less perturbed compared with the rate of force development following small to moderate reductions in tissue temperature. This suggestion considers that applied CWI protocols (8-15°C and 3-20 min) do not extensively decrease muscle temperatures beyond resting levels (Allan et al., , 2017Choo et al., 2018;Ihsan et al., 2020;Mawhinney et al., 2013) and presumably do not result in extensive decreases in muscle force production as demonstrated in mechanistic studies assessing the influence of tissue temperature on muscle contractility (Bergh & Ekblom, 1979;De Ruiter et al., 1999;Sargeant, 1987). ...
This review evaluated the effect of CWI on the temporal recovery profile of physical performance, accounting for environmental conditions and prior exercise modality. Sixty-eight studies met the inclusion criteria. Standardised mean differences were calculated for parameters assessed at <1, 1-6, 24, 48, 72 and ≥96 h post-immersion. CWI improved short-term recovery of endurance performance (p = 0.01, 1 h), but impaired sprint (p = 0.03, 1 h) and jump performance (p = 0.04, 6h). CWI improved longer-term recovery of jump performance (p < 0.01-0.02, 24 h and 96 h) and strength (p < 0.01, 24 h), which coincided with decreased creatine kinase (p < 0.01-0.04, 24-72 h), improved muscle soreness (p < 0.01-0.02, 1-72 h) and perceived recovery (p < 0.01, 72 h). CWI improved the recovery of endurance performance following exercise in warm (p < 0.01) and but not in temperate conditions (p = 0.06). CWI improved strength recovery following endurance exercise performed at cool-to-temperate conditions (p = 0.04) and enhanced recovery of sprint performance following resistance exercise (p = 0.04). CWI seems to benefit the acute recovery of endurance performance, and longer-term recovery of muscle strength and power, coinciding with changes in muscle damage markers. This, however, depends on the nature of the preceding exercise.
... The idea of a passive warm-up has surfaced, with the intention of conserving energy substrates normally used in an active warm-up, while still increasing intramuscular temperature (Bishop, 2003;Bergh, & Ekblom, 1979;De Ruiter, & De Hann, 2000;Kilduff et al., 2012). ...
... Our decision to utilize 10% was due to the results of a study conducted by Stone et al. indicating the optimal load for a loaded jump squat is 10%, and that increasing load produced lower power outputs (Stone et al., 2003). Also consistent with prior research, Passive temperature effects may be superior to a control group, but they do not appear to be superior to a PAP warm-up (Bishop, 2003;Kilduff et al., 2013;Bergh, & Ekblom, 1979;Mohr et al., 2004). Future research might also investigate the effects of an abbreviated PAP, or active warm-up preceded by a passive warm-up in comparison to other approaches. ...
Warm-ups are an essential element of exercise and sport performance. Although research has demonstrated benefits associated with active warm-ups, research investigating the effects of a passive warm-up on subsequent performance is limited. The purpose of this study is to compare the effects of an active, post-activation potentiation (PAP) warm-up to a passive warm-up on vertical jump performance. Study participants were randomly assigned to one of two groups. Each group performed both the active and passive warm-ups, in reverse order, to control for order effect. Participants in this study consisted of 20 college students (men and women) between the ages of 18 and 35 years who were well-trained and anaerobically fit. A repeated measures ANOVA revealed a statistically significant main effect difference in vertical jump measures (F=16.148, p<0.001). Further analysis of the results demonstrated that between the three treatments tested, control, active, passive, there was a statically significant difference between the active warm-up when compared to both the passive and control warm-ups (p=0.004; p<0.001). The results also indicated that there was practical significance between the active and passive treatment as well as the control group (partial eta squared=0.459). In conclusion, an active warm-up prior to vertical jump testing appears to be superior to a passive warm-up. Physiologically the body may perform better following dynamic movements rather than through a passive increase in intramuscular temperature. Prior to athletic events, we recommend athletes perform warm-ups utilizing dynamic movements rather than using a heating system alone.
... The elevation of skin and muscle temperature is frequently referenced as having a beneficial effect on high-intensity, intermediate duration (10 s to 5 min) activity. 1 Specific to short-term maximal power production, higher peripheral muscle temperatures increase maximal twitch and relaxation rate 2 and nerve conduction velocity. 3 These factors contribute to the numerous examples of increased muscle temperatures improving performance in jumps [4][5][6] and maximal cycling sprints from 6-second 7 to 20-second to 30-second efforts. [8][9][10] These enhancements have primarily been attributed to a rightward shift in the force-velocity curve at higher body temperatures. ...
... To our knowledge, this is one of the first studies to investigate the relationship between skin or muscle temperature and upper limb power generating capacity and the first to use a pulling movement. [4]). World record ratio was calculated using previously described methods. ...
Purpose:
Determine the effects of skin temperature change on bench-pull power following a passive warm-up intervention with highly trained swimmers using multiple heated clothing garments.
Methods:
Using a crossover design, 8 high-performance swimmers (mean [SD]; age, 22.4 [4.4] y; body mass, 74.9 [8.1] kg; height, 1.79 [0.09] m; world record ratio, 107.3% [5.1%]) completed a pool-based warm-up followed by a 35-minute transition phase before completing 3 repetitions at 50% of 1-repetition maximum of the bench-pull exercise. During transition, swimmers wore either a warm (control) or a heated (heat) clothing condition.
Results:
Following heating, mean skin temperature was 0.7 °C higher in heat (P = .011), though no change was seen in tympanic temperature. Bench-pull mean and peak power improved by 4.5% and 4.7% following heating, respectively. A large repeated-measures correlation was observed between skin temperature and mean (r [90% CI] = .94 [.65 to .99], P < .01) and peak (r [90% CI] = .89 [.45 to .98], P < .01) power output. Thermal sensation and comfort at all regions were higher with heating (P ≤ .02).
Conclusion:
Combined upper- and lower-limb passive heating can increase whole-body skin temperature and improve short-duration upper-limb power output during the bench-pull exercise. Improvements in power output were directly related to the skin temperature increase facilitated by the heated clothing.
... The deterioration of physical performance due to adverse environmental conditions, such as when the athlete feels cold or wet (pre-immersion), has been observed in other studies, especially during exercises executed at high intensity (Bergh and Ekblom 1979;Howard et al. 1994;Schniepp et al. 2002). Contrary to these results, Marsh and Sleivert (1999) found an increase in power after performing pre-immersion for 30 min at a temperature between 12 ºC and 18 ºC. ...
... The authors highlighted that in high-speed situations, a slight alteration in the agonist/antagonist balance can impair the coordination of movements and hinder an adequate production of force. Bergh and Ekblom (1979), on the other hand, did not nd alterations in the EMG signal during exercise in cycloergometer after muscular cooling from 38 ºC to 30 ºC; however, they veri ed a decrease of 4-6% in the power produced for each 1 ºC of reduction in the muscular temperature. In this sense, muscle cooling seems to impair performance, especially at high velocities of muscle contraction ) by reducing pedaling frequency. ...
While an exercise recovery method may be beneficial from a physiological point of view, it may be detrimental to subsequent anaerobic performance. To investigate the energetic responses of water immersion at different temperatures during post-exercise recovery and its consequences on subsequent anaerobic performance. A randomized and controlled crossover experimental design was performed with 21 male trained cyclists and triathletes. Participants were assigned randomly to receive three passive recovery strategies during 10 min after a Wingate Anaerobic Test (WAnT): outside water immersion (OWI), cold water immersion (CWI: 20ºC), and hot water immersion (HWI: 40ºC). Blood lactate, cardiorespiratory, and mechanical outcomes were measured during the WAnT and its recovery. Time constant (τ), asymptotic value, and area under the curve (AUC) were quantified for each physiologic parameter during recovery. After that, a second WAnT test and 10-min recovery were realized in the same session. Regardless the water immersion temperature, the water immersion increased τVo 2 (+18%), asymptote (Vo 2 +16%, Vo 2 +13%, V E +17%, HR +16%) and AUC (Vo 2 +27%, Vco 2 +18%, V E +20%, HR +25%), while decreased τHR (-33%). There was no influence of water immersion on blood lactate parameters. HWI improved the mean power output during the second WAnT test (2.2%), while the CWI decreased by 2.4% ( P < 0.01). Independent of the water temperature, water immersion enhanced aerobic energy recovery without modifying blood lactate recovery. However, subsequent anaerobic performance was increased only during HWI and decreased during CWI. Despite being higher than in other studies, 20°C during CWI effectively triggered physiological and performance responses via an easier-to-administer temperature. Water immersion-induced physiological changes did not predict subsequent anaerobic performance. The action of immersion temperature on muscle neuromechanics and its repercussions on the force-velocity relationship seem to explain the changes of anaerobic mechanical power.
... Namely changes in: temperature (lower deep body, muscle and skin temperature); metabolism (increased lactate, low glucose, fasting and increasedVO 2 /reduced economy); and central/peripheral circulation (reduced maximal heart rate, lower cardiac output and reduced muscle blood flow) (6). Although the individual extent to which each of these mechanisms impairs performance is not fully understood, a decrease in the different physiological temperatures seem to affect endurance exercise capacity (4,8). Skin temperature (T skin ) appears to be particularly important, as a larger gradient between T core and T skin is indicative of a higher heat loss. ...
... In our case, with POST T skin dropping below 31 • C for the thigh, back and anterior thorax, it is probable that the subcutaneous muscle tissues underneath also suffered from a drop in temperature or at least from a reduced increase in temperature in the working muscle. It is well documented that a reduced muscle temperature influences performance negatively (4,8,26). Moreover, it has been shown that during moderateintensity exercise in the cold where T skin is reduced, muscle temperature increases to a lesser extent than during the same exercise intensity in warmer conditions (27)(28)(29). ...
Introduction
When exercising in the cold, optimizing thermoregulation is essential to maintain performance. However, no study has investigated thermal parameters with wearable-based measurements in a field setting among elite Nordic skiers. Therefore, this study aimed to assess the thermal response and sensation measured at different body parts during exercise in a cold environment in biathletes.
Methods
Thirteen Swiss national team biathletes (6 females, 7 males) performed two skiing bouts in the skating technique on two consecutive days (ambient temperature: −3.74 ± 2.32 °C) at 78 ± 4% of maximal heart rate. Heat flux (HF), core (Tcore) and skin (Tskin) temperature were measured with sensors placed on the thigh, back, anterior and lateral thorax. Thermal sensation (TS) was assessed three times for different body parts: in protective winter clothing, in a race suit before (PRE) and after exercise (POST).
Results
HF demonstrated differences (p < 0.001) between sensor locations, with the thigh showing the highest heat loss (344 ± 37 kJ/m²), followed by the back (269 ± 6 kJ/m²), the lateral thorax (220 ± 47 kJ/m²), and the anterior thorax (192 ± 37 kJ/m²). Tcore increased (p < 0.001). Tskin decreased for all body parts (p < 0.001). Thigh Tskin decreased more than for other body parts (p < 0.001). From PRE to POST, TS of the hands decreased (p < 0.01).
Conclusion
Biathletes skiing in a race suit at moderate intensity experience significant heat loss and a large drop in Tskin, particularly at the quadriceps muscle. To support the optimal functioning of working muscles, body-part dependent differences in the thermal response should be considered for clothing strategy and for race suit design.
... Muscle temperature significantly impacts athletic performance [24][25][26][27][28][29]; there is a general idea that the higher the muscle temperature, the better the force-generating capacity [24,30]. For example, a 1 °C difference in muscle temperature could affect up to 4% [25] or 10% [29] of athletic performance. ...
... Muscle temperature significantly impacts athletic performance [24][25][26][27][28][29]; there is a general idea that the higher the muscle temperature, the better the force-generating capacity [24,30]. For example, a 1 °C difference in muscle temperature could affect up to 4% [25] or 10% [29] of athletic performance. In our study, the thigh temperatures were consistently increased when performing cycling sprints (during sets 1 through 5 regardless of condition: 32.8 °C, 33.0 °C, 33.4 °C, 33.7 °C, and 34.0 °C, respectively), and the cycling performance peaked at set 2 ( Figure 3). ...
We compared the effect of bilateral knee joint cooling with or without a pre-cooling warm-up on sprint cycling performance to a non-cooling control condition. Seventeen healthy young males (25 ± 2 years, 174 ± 6 cm, 70 ± 9 kg) performed three conditions in a counterbalanced order (condition 1: warming + cooling + cycling; condition 2: cooling + cycling; condition 3: cycling). For warming, a single set of cycling intervals (a 10 s sprint with maximal effort followed by a 180 s active recovery; resistive load 4% and 1% body mass for sprint and recovery, respectively) was performed. For cycling, five sets of cycling intervals were performed. For cooling, 20 min of bilateral focal knee joint cooling was applied. Peak and average values of anaerobic capacity and wheel cadence during each set across conditions were statistically compared. There was no condition effect over set (condition × set) in anaerobic capacity (F8,224 < 1.49, p > 0.16) and wheel cadence (F8,224 < 1.48, p > 0.17). Regardless of set (condition effect: F2,224 > 8.64, p < 0.0002), conditions 1 and 2 produced higher values of anaerobic capacity (p ≤ 0.05). Similarly (condition effect: F2,224 > 4.62, p < 0.02), condition 1 showed higher wheel cadence (p < 0.02) than condition 3. A bilateral joint cooling for 20 min with or without pre-cooling warm-up may improve overall sprint cycling capacity during five sets of cycling intervals when compared to the non-cooling condition.
... One line of thought is rooted in evidence that skeletal muscle performance depends on maintaining an optimal temperature range (Sargeant, 1987). Muscle function appears to deteriorate if muscle temperature moves above or below certain limits, as observed in early investigations that demonstrated a decline in physical performance outside a narrow thermal window (Bergh & Ekblom, 1979). During strenuous exercise, localized cooling may counteract excessive heat accumulation, thus enabling muscles to remain within a favorable thermal range. ...
Intermittent palm (PC) and sole cooling (SC) are emerging techniques with potential ergogenic effects under high-intensity and fatiguing exercise conditions. However, evidence regarding their efficacy remains inconclusive. This systematic review and meta-analysis aims to summarize the acute effects of intermittent PC and SC applied during inter-set rest periods on resistance training volume and rate of perceived exertion (RPE) in healthy individuals. A systematic literature search in the electronic databases Cochrane, PubMed, Scopus, SPORTDiscus, and Web of Science identified 10 studies (n = 182 participants, 40 female, mean age range: 19 – 26 years). Effect sizes (Cohen’s dz) were calculated for each study and corrected for small sample bias (Hedges g). Meta-analyses were conducted using a random-effects model and an inverse variance method. PC and SC were applied for 1–3 min (2.3 ± 0.7 min) with temperatures ranging from 10–15 °C (12.0 ± 2.2 °C). Based on the current literature, no significant effect of PC or SC on resistance training volume was observed (n = 12, g = 0.22, 95%CI [-0.27, 0.72], p = 0.345), with high heterogeneity values indicating considerable variability among studies. Furthermore, no significant effect of PC or SC on RPE was found (n = 9, g = 0.10, 95%CI [-0.15, 0.32], p = 0.389). Based on current evidence, intermittent PC and SC cannot be generally recommended for resistance training volume enhancement.
... Warm-up and breaks in competition Athletes regularly complete a warm-up prior to competition, completing bouts of exercise that increase core body and muscle temperature (Saltin et al. 1968). Elevated muscle temperature increases muscle force and power production in isolated rat muscle in vitro (Ranatunga 1998), while in humans, power production during a vertical jump and sprint cycling increases by 2%-10% per • C increase of muscle temperature between ∼30 and 39 • C (Bergh and Ekblom 1979;Sargeant 1987). These improvements occur due to intramuscular increase in calcium influx and sensitivity along with increases in intracellular fluid that improves both voluntary and involuntary muscle force output in the heated muscle (Rodrigues et al. 2023). ...
Exercise and passive heating share some acute physiological responses. These include increases in body temperature, sweat rate, blood flow, heart rate, and redistribution of plasma and blood volume. These responses can vary depending on the heating modality or dose (e.g., temperature, duration, body coverage) and are beneficial to athletes in specific scenarios. These scenarios include being applied to increase muscle or force production, induce rapid weight loss, stimulate thermoregulatory or cardiovascular adaptation, or to accelerate recovery. The rationale being to tailor the specific passive heating protocol to target the desired physiological response. However, some acute responses to passive heating may also be detrimental to sporting outcomes, such as exercising in the heat, having unintended residual negative effects on performance or perceptions of fatigue, or even resulting in hospitalisation if implemented inappropriately. Accordingly, the effects of passive heating should be carefully considered prior to implementation by athletes, coaches, and support staff. Therefore, the purpose of this review is to evaluate the physiological responses to different modes and doses of passive heating and explore the various sport contexts where these effects may either benefit or hinder athletes. Understanding these responses can aid the implementation of passive heating in sport and identify potential recommended heating protocols in each given scenario.
... Other mechanisms such as increased muscle temperature [11] may also contribute to BPT improvements, more so in the SLOW condition. Resistance exercise has been shown to elevate both muscle and skin temperatures [53,54], and muscle temperature positively correlates with power performance [55,56]. Increased muscle temperatures are linked with increased sEMG amplitude [57], higher firing rates [58], enhanced anaerobic ATP turnover rates, and contractile efficiency of muscle fibers [59]. ...
Background: The tempo of resistance exercises is known to influence performance outcomes, yet its specific effects on post-activation performance enhancement (PAPE) remain unclear. This study aimed to investigate the effects of fast versus slow repetitions at a load of 70% of one-repetition maximum (1-RM) in the bench press exercise, focusing on velocity, surface electromyographic (sEMG) activity, and applied force while equating time under tension on bench press throw performance. Methods: Eleven men (age: 23.5 ± 5.4 years, height: 1.79 ± 0.04 m, body mass: 79.1 ± 6.4 kg, maximum strength 1-RM: 91.0 ± 12.0 kg) participated. Two experimental conditions (FAST and SLOW) and one control (CTRL) were randomly assigned. Participants performed two sets of six repetitions as fast as possible (FAST condition) and two sets of three repetitions at a controlled tempo (SLOW condition) at half the concentric velocity of FAST, as determined in a preliminary session. Before and after the bench press participants performed bench press throws tests (Pre, 45 s, 4, 8, and 12 min after). Results: sEMG activity and peak force during the bench press were higher in FAST vs. SLOW conditioning activity (p < 0.001), with time under tension showing no significant differences between conditions (p > 0.05). Mean propulsive velocity (MPV) during the bench press throw improved equally in both FAST and SLOW conditions compared with baseline from the 4th to the 12th min of recovery (FAST: +6.8 ± 2.9% to +7.2 ± 3.3%, p < 0.01, SLOW: +4.0 ± 3.0% to +3.6 ± 4.5%, p < 0.01, respectively). Compared to the CTRL, both conditions exhibited improved MPV values from the 4th to 12th min (p < 0.01). Peak velocity improvements were observed only after the FAST condition compared to the baseline (p < 0.01) with no differences from SLOW. For all muscles involved and time points, sEMG activity during bench press throws was higher than CTRL in both experimental conditions (p < 0.01), with no differences between FAST and SLOW. Peak force increased in both FAST and SLOW conditions at all time points (p < 0.05), compared to CTRL. Conclusions: These findings suggest that post-activation performance enhancement is independent of movement tempo, provided that the resistive load and total time under tension of the conditioning activity are similar. This study provides valuable insights into the complex training method for athletes by demonstrating that varying tempo does not significantly affect post-activation performance enhancement when load and TUT are equated.
... Water immersion methods cause's athletes to feel more relaxed and this issue can happen due to the floating force that is oppose of gravity and supports the part of body weight that is floating in water. Exposure to a cold-water immersion intervention can rapidly decrease muscle temperature and muscular force output (Bergh, 1979) The shuttlers have lower fat mass in lower body i.e. lower will be the adipose tissue which will act as an insulator, the legs' reduced subcutaneous body fat would have permitted more connective heat escape from these muscles which lowers the (Peiffer, 2009). Also periffer's studies result support the concept of Coldwater immersion significantly lowered temperature after the recovery phase (Periffer, 2011). ...
The purpose of the study was to find out the effects of foam rolling and cold-water immersion (CWI) recovery method on selected physiological condition after matches among badminton players. A total 30 subjects were purposely selected from the Degree College of Physical Education Amravati and were divided into 3 groups of 10 subjects each. The study was delimited to male players only age ranged 18 to 25 years. The selected dependent variables for the study were Lactic Acid, Heart rate and Breathing rate. Foam roller and CWI were taken as independent variables. The reading of Lactic acid, Heart rate and Breathing rate were measured and recorded accordingly after match and after Recovery method. The subjects performed different recovery method on different days. The data for selected physiological variables were collected pre and post recovery methods. Capillary blood samples were taken for lactic acid, breathing rate and heart rate were measured manually. The data was analyzed through two-way mixed ANOVA at 0.05 level of significance. The study overall concludes that foam rolling recovery modality can be preferred in place of cold-water therapy for recovery process. The major physiological change i.e. lower lactic acid allows a shuttler to recover faster and get ready for another match in the same day. As the rough surface of the roller apply specific pressure at specific muscle which allows the proper blood flow at that particular area further it removes all the edema which occur at the time of playing, it increases inflammatory responses. By observing the result of the study one can say that the shuttlers can prefer to do foam rolling at the time of recovery.
... Apart from the varied terrain, skiing and snowboarding are performed in relatively cold environments (−20 to 10 • C) [8]. Considering the cold has been shown to reduce muscle power [3], strength [9], proprioception [10] and rate of force development [11], the combination of these reductions with the physical demands of skiing and snowboarding may leave the athlete's musculoskeletal system in a very vulnerable state [8]. In fact, the 2 of 9 cold has been associated with an increased risk of knee injury in female skiers [8]. ...
Exposure to the cold can negatively affect muscle performance. This study compared the effects of two different full-length, lower body, next-to-skin garments on thermal sensation, countermovement jump (CMJ) height and knee frontal plane angle upon landing following cold exposure against a control. After familiarisation, 13 male and 11 female recreationally active adults attended three separate laboratory testing sessions where a randomly assigned next-to-skin garment was used (compression, thermal and control (shorts)). A pre- and post-testing protocol comprising CMJ and drop landings interspersed with a sedentary cooling period of 40 min at 0 °C was adopted. High-speed motion analysis and subjective ratings of thermal sensation were recorded. Exposure to the cold significantly reduced thermal sensation (p < 0.001) scores and CMJ height (p < 0.001). Only female participants felt significantly warmer (p ≤ 0.009) in the next-to-skin garments. Losses in CMJ height were significantly reduced by the next-to-skin garments compared to the control with the thermal garment producing better results. There was little change in knee frontal plane angle upon landing in all the garments tested. Ambient cooling at 0 °C for 40 min had a significant effect on CMJ height and thermal sensation but not knee valgus upon landing. Participants in winter sports should consider next-to-skin garments in conjunction with proper warm-ups and re-warming techniques to protect themselves from the negative effects of the cold.
... Previous research has established that muscle function is influenced by muscle temperature, with studies indicating that jumping and sprinting performance is compromised at lower muscle temperatures (<36 • C) and enhanced at slightly elevated temperatures (>36 • C). For instance, [22] demonstrated that higher muscle temperatures are associated with improved sprint performance, a finding corroborated by subsequent research involving isokinetic cycling [4]. Crucially, it is still debated, whether or not resistance exercise reliably produces a notable increase in core temperature, specifically in relation to the employed training parameters, i.e., the load, number of sets, and number of repetitions [23]. ...
Intermittent palm (PC) and sole cooling (SC) are proposed ergogenic methods for enhancing exercise performance during high-intensity and fatiguing conditions. However, findings in the literature regarding its positive effect remain inconclusive. This study aimed at investigating the effects of intermittent PC and SC compared to no cooling (NC) on acute training volume during resistance exercise, particularly focusing on the total number of repetitions (TR) performed. Three separate randomized crossover protocols, incorporating commonly practiced resistance exercises (Protocol 1: pullups; Protocol 2: pushups; Protocol 3: leg extensions), were conducted, enrolling healthy, physically active adults (overall sample: n = 41 (12 female), age: 23.9 ± 4.0 years (mean ± SD), height: 174.4 ± 9.5 cm, body mass: 69.3 ± 12.4 kg). During Protocol 3, tympanic temperature (TT), rate of perceived exertion (RPE), and electromyography (EMG) of quadriceps muscles were additionally assessed for SC. PC resulted in less TR compared to NC in Protocol 1 (p < 0.001). Protocol 2 and 3 did not reveal significant ergogenic benefits of PC or SC compared to NC (p > 0.05). Furthermore, SC had no effect on TT, RPE, or EMG amplitudes (all p > 0.05). The inconsistent findings suggest that intermittent PC and SC might have limited effectiveness in enhancing training volume during resistance exercise in physically active adults. Future research should examine various resistance training protocols under controlled conditions, and incorporate comprehensive physiological measurements to elucidate the potential benefits and mechanisms of intermittent cooling in resistance exercise contexts.
... The result of a combination of lowered skin temperature and reflex cutaneous vasoconstriction is the decreased temperature of peripheral nerves and muscle tissues, which can lead to significant impairment and reduced efficiency (66). For every 10 C decrease in local temperature, peripheral nerve conduction velocity decreases by $15 m·s À1 (67), while maximal muscle power and mechanical efficiency fall by 3% for every 1 C decrease in muscle temperature (68). This results in notable performance decrements such as impaired ability to complete fine-motor tasks (69) and altered motor unit recruitment patterns resulting in weaker muscle contraction (70). ...
Effective execution of military missions in cold environments requires highly trained, well-equipped, and operationally ready service members. Understanding the metabolic energetic demands of performing physical work in extreme cold conditions is critical for individual medical readiness of service members. In this narrative review, we describe 1) the extreme energy costs of performing militarily relevant physical work in cold environments, 2) key factors specific to cold environments that explain these additional energy costs, 3) additional environmental factors that modulate the metabolic burden, 4) medical readiness consequences associated with these circumstances, and 5) potential countermeasures to be developed to aid future military personnel. Key characteristics of the cold operational environment that cause excessive energy expenditure in military personnel include thermoregulatory mechanisms, winter apparel, inspiration of cold air, inclement weather, and activities specific to cold weather. The combination of cold temperatures with other environmental stressors, including altitude, wind, and wet environments exacerbates the overall metabolic strain on military service members. The high energy cost of working in these environments increases the risk of undesirable consequences, including negative energy balance, dehydration, and subsequent decrements in physical and cognitive performance. Such consequences may be mitigated by the application of enhanced clothing and equipment design, wearable technologies for biomechanical assistance and localized heating, thermogenic pharmaceuticals, and cold habituation and training guidance. Altogether, the reduction in energy expenditure of modern military personnel during physical work in cold environments would promote desirable operational outcomes and optimize the health and performance of service members.
... Reilly and Down, 1986;Rodahl et al., 1976). While a number of factors have been proposed to underlie these performance impacting effects of time-of-day, including body temperature (Bergh and Ekblom, 1979;Harrison and Bers, 1989), motor unit recruitment (Gueldich et al., 2017;Nicolas et al., 2007;Sedliak et al., 2008), and meal timing/muscle glycogen status (Kerksick et al., 2017;Koch et al., 2020), an emphasized point in the field is that variation in exercise performance is due to circadian fluctuations in the intrinsic properties of skeletal muscle (Douglas et al., 2021). In contrast to this, recent work found that the maximal intrinsic force generating capacity of the mouse extensor digitorum longus (EDL) is not different between two different times of the light phase (i.e. ...
A growing body of data suggests that skeletal muscle contractile function and glucose metabolism vary by time-of-day, with chronobiological effects on intrinsic skeletal muscle properties being proposed as the underlying mediator. However, no studies have directly investigated intrinsic contractile function or glucose metabolism in skeletal muscle over a 24 h circadian cycle. To address this, we assessed intrinsic contractile function and endurance, as well as contraction-stimulated glucose uptake, in isolated extensor digitorum longus and soleus from female mice at four times-of-day (Zeitgeber Times 1, 7, 13, 19). Significantly, while both muscles demonstrated circadian-related changes in gene expression, intrinsic contractile function, endurance, and contraction-stimulated glucose uptake were not different between the four time points. Overall, these results demonstrate that time-of-day variation in exercise performance and the glycemia-reducing benefits of exercise are not due to chronobiological effects on intrinsic muscle function or contraction-stimulated glucose uptake.
Impact statement
Ex vivo testing demonstrates that there is no time-of-day variation in the intrinsic contractile properties of skeletal muscle (including no effect on force production or endurance) or contraction-stimulated glucose uptake.
... In contrast, the halftime leg press drill had little impact on players' short-passing ability. Similarly, randomized crossover research by Kaya et al. (2021) revealed that halftime foam-axis rolling drills had no positive impact on players' short-passing ability [64,65]. Nevertheless, due to the lower intensity, foam-axis rolling training and leg press training during halftime tend to reduce muscle temperature in athletes who have recently concluded a game's first half. ...
Objective
This study synthesizes evidence from the Loughborough Passing Test to evaluate the short-passing ability of soccer players and summarizes the reported variables that affect this ability to provide support for the development and improvement of short-passing abilities in soccer players.
Methods
In this systematic review using the PRISMA guidelines, a comprehensive search was conducted in Web of Science, PubMed, and EBSCOhost from inception to July 2023 to identify relevant articles from the accessible literature. Only studies that used the Loughborough test to assess athletes' short-passing ability were included. The quality of the included studies was independently assessed by two reviewers using the PEDro scale, and two authors independently completed the data extraction.
Results
Based on the type of intervention or influencing factor, ten studies investigated training, nine studies investigated fatigue, nine studies investigated supplement intake, and five studies investigated other factors.
Conclusion
Evidence indicates that fitness training, small-sided games training, and warm-up training have positive effects on athletes' short-passing ability, high-intensity special-position training and water intake have no discernible impact, mental and muscular exhaustion have a significantly negative effect, and the effect of nutritional ergogenic aid intake is not yet clear. Future research should examine more elements that can affect soccer players' short-passing ability.
Trial registration
https://inplasy.com/., identifier: INPLASY20237.
... It is a well established fact that warm-up exercise results in a significant increase in the force-generating capacity of skeletal muscle (Bergh and Ekblom, 1979). In particular, the basic premise of the warm-up effect is addressed by the temperature-related mechanism (Asmussen and Bøje, 1945;Bishop, 2003), which primarily addresses peripheral changes in muscle physiology, such as muscle metabolism along with the blood flow (Gray et al., 2011), and muscle fiber conduction velocity (Pearce et al., 2012), by increasing muscle temperature. ...
In this study, we tested several hypotheses related to changes in motor unit activation patterns after warm-up exercise. Fifteen healthy young men participated in the experiment and the main task was to produce voluntary torque through the elbow joint under the isometric condition. The experimental conditions consisted of two directions of torque, including flexion and extension, at two joint angles, 10° and 90°. Participants were asked to increase the joint torque to the maximal level at a rate of 10% of the maximum voluntary torque. The warm-up protocol followed the ACSM guidelines, which increased body temperature by approximately 1.5°C. Decomposition electromyography electrodes, capable of extracting multiple motor unit action potentials from surface signals, were placed on the biceps and triceps brachii muscles, and joint torque was measured on the dynamometer. The mean firing rate and the recruitment threshold of the decomposed motor units were quantified. In addition, a single motor unit activity from the spike train was quantified for each of five selected motor units. The magnitude of joint torque increased with the warm-up exercise for all the experimental conditions. The results of the motor unit analyses showed a positive and beneficial effect of the warm-up exercise, with an increase in both the mean firing rate and the recruitment threshold by about 56% and 33%, respectively, particularly in the agonist muscle. Power spectral density in the gamma band, which is thought to be the dominant voluntary activity, was also increased by the warm-up exercise only in the high threshold motor units.
... In this regard, it should be noted that while passive stiffness is primarily related to the mechanical properties of the elastic components (i.e. both parallel and series elastic components) but also the ever-present weakly bound cross-bridges, active stiffness essentially relates to parallel muscle contraction force, derived from cross-bridges. 27,28 Although warmup and stretching studies have been shown to decrease the passive shear modulus, these two interventions could produce a different response on force production since the warmup increases muscle temperature, which has a positive effect on force production, 29 while static stretching reduces the maximal voluntary force. 30 The purpose of this study was to determine the acute effects of static stretching and conventional warmup protocols on the active and passive shear modulus of the hamstring muscles. ...
... Although PH does not increase force production during involuntary tetanic contractions, and voluntary isometric and isokinetic contractions, ours results indicate that increased Tmu enhances muscle contractile properties (especially muscle relaxation) and induces a shift towards a faster contractile phenotype. These Tmu-mediated changes in muscle function may be beneficial for acute explosive exercises (Asmussen et al., 1976;Bergh and Ekblom, 1979). However, elevated Tmu impairs fatigue resistance during repeated involuntary contractions, suggesting that passive muscle heating could increase muscle force decline during repetitive explosive exercises and intense cyclic exercises. ...
Background: We investigated the impact of 1) passive heating (PH) induced by single and intermittent/prolonged hot-water immersion (HWI) and 2) the duration of PH, on muscle contractile function under the unfatigued state, and during the development of muscle fatigue.
Methods: Twelve young males volunteered for this study consisting of two phases: single phase (SP) followed by intermittent/prolonged phase (IPP), with both phases including two conditions (i.e., four trials in total) performed randomly: control passive sitting (CON) and HWI (44–45°C; water up to the waist level). SP-HWI included one continuous 45-min bath (from 15 to 60 min). IPP-HWI included an initial 45-min bath (from 15 to 60 min) followed by eight additional 15-min baths interspaced with 15-min breaks at room temperature between 75 and 300 min. Intramuscular (Tmu; measured in the vastus lateralis muscle) and rectal (Trec) temperatures were determined. Neuromuscular testing (performed in the knee extensors and flexors) was performed at baseline and 60 min later during SP, and at baseline, 60, 90, 150 and 300 min after baseline during IPP. A fatiguing protocol (100 electrical stimulations of the knee extensors) was performed after the last neuromuscular testing of each trial.
Results: HWI increased Tmu and Trec to 38°C–38.5°C (p < 0.05) during both SP and IPP. Under the unfatigued state, HWI did not affect electrically induced torques at 20 Hz (P20) and 100 Hz (P100). However, it induced a shift towards a faster contractile profile during both SP and IPP, as evidenced by a decreased P20/P100 ratio (p < 0.05) and an improved muscle relaxation (i.e., reduced half-relaxation time and increased rate of torque relaxation; p < 0.05). Despite a reduced voluntary activation (i.e., −2.63% ± 4.19% after SP-HWI and −5.73% ± 4.31% after IPP-HWI; condition effect: p < 0.001), HWI did not impair maximal isokinetic and isometric contraction torques. During the fatiguing protocol, fatigue index and the changes in muscle contractile properties were larger after HWI than CON conditions (p < 0.05). Finally, none of these parameters were significantly affected by the heating duration.
Conclusion: PH induces changes in muscle contractile function which are not augmented by prolonged exposure when thermal stress is moderate.
... Although performance was not measured in this study, it is well-established that muscle temperature and muscle function are related (Bergh and Ekblom 1979;Davies et al. 1982;Sargeant 1987). The attenuation in muscle temperature when using the passive heat intervention may lead to an improved performance via improved myosin adenosine triphosphatase activity. ...
Purpose
Soccer substitutes are exposed to periods of limited activity before entering match-play, likely negating benefits of active warm-ups. This study aimed to determine the effects of using a passive heat intervention following a pre-match, and half-time warm-up, on muscle and core temperature in soccer players during ambient (18 °C) and cold (2 °C) conditions.
Methods
On four occasions, 8 male players, completed a pre-match warm-up, followed by 45 min of rest. Following this, participants completed a half-time re-warm-up followed by an additional 45 min of rest, simulating a full match for an unplaying substitute. During periods of rest, participants wore either standardised tracksuit bottoms (CON), or heated trousers (HEAT), over typical soccer attire.
Results
Vastus lateralis temperature declined less in HEAT compared to CON following the 1st half in 2 °C (Δ − 4.39 ± 0.81 vs. − 6.21 ± 1.32 °C, P = 0.002) and 18 °C (Δ − 2.48 ± 0.71 vs. − 3.54 ± 0.88 °C, P = 0.003). These findings were also observed in the 2nd half for the 2 °C (Δ − 4.36 ± 1.03 vs. − 6.26 ± 1.04 °C, P = 0.002) and 18 °C (Δ − 2.85 ± 0.57 vs. − 4.06 ± 1 °C, P = 0.018) conditions. In addition, core temperature declined less in HEAT compared to CON following the 1st (Δ − 0.41 ± 0.25 vs. − 0.84 ± 0.41 °C, P = 0.037) and 2nd (Δ − 0.25 ± 0.33 vs. − 0.64 ± 0.34 °C, P = 0.028) halves of passive rest in 2 °C, with no differences in the 18 °C condition. Perceptual data confirmed that participants were more comfortable in HEAT vs. CON in 2 °C (P < 0.01).
Conclusions
Following active warm-ups, heated trousers attenuate the decline in muscle temperature in ambient and cold environments.
... This may be due to the fact that muscle movement becomes sluggish with the decrease in temperature when a drop jump is performed at LT conditions [43]. This phenomenon can be explained by the results of Bergh et al. [44], who showed a 4.2% decrease in muscle explosive power for every 1 • C decrease in core temperature. In addition, Oksa et al. [45] also showed that muscle temperature decreased at LT conditions, which in turn led to a significant decrease in VJ takeoff time. ...
This study aimed to determine whether drop jump height will affect the post-activation performance enhancement (PAPE) effect at room temperature (RT) and low temperature (LT) conditions. Twelve male strength-trained males participated in this study. Prior to warm-up, subjects underwent a 30 min period of environmental adaptation. Different warm-up protocols were used at different ambient temperatures to help subjects achieve a level of muscle activity and body temperature similar to their daily training. After the pre-test, each subject participated in six experimental sessions at either RT or LT conditions, respectively, which were separated by at least 72 h and conducted at the same time of day to control for circadian influences on metabolism. After the conditioning activities, vertical jump (VJ) performance was re-tested at 4 min, 8 min, and 12 min of passive recovery to assess transient potentiation effects. Under RT conditions, 60 cm and 90 cm drop jumps could induce PAPE, with the PAPE effect being most significant at 4 min (p < 0.01) and 8 min (p < 0.01), respectively, while a 30 cm drop jump could not induce PAPE. Under LT conditions, 30 cm and 90 cm drop jumps could not induce PAPE, and VJ performance gradually declined over time (p < 0.01). However, although a 60 cm drop jump could not induce PAPE, VJ performance was not affected by LT at 8 min and declined at 12 min (p < 0.05). This study demonstrated that 60 cm and 90 cm drop jumps can be used to induce PAPE at RT conditions. LT can impair PAPE induction, while a 60 cm drop jump can be utilized for warm-up at LT conditions to counteract the effects of LT on athletic performance.
... It is notable that increases in muscle temperature enhance cross-bridge cycling rates, reducing net mechanical efficiency (Ferguson et al., 2002) and subsequently increasing muscular power output during brief or higher-speed/higher-intensity exercise (Bergh & Ekblom, 1979;Ferretti et al., 1992;Sargeant, 1987). So larger muscles that work at higher speeds through larger ranges and with smaller surface area-to-volume ratios might provide an advantage to humans (or other animals) in communities in which such activities predominate over endurance-type behaviours. ...
Elastic strain energy that is stored and released from long, distal tendons such as the Achilles during locomotion allows for muscle power amplification as well as for reduction of the locomotor energy cost: as distal tendons perform mechanical work during recoil, plantar flexor muscle fibres can work over smaller length ranges, at slower shortening speeds, and at lower activation levels. Scant evidence exists that long distal tendons evolved in humans (or were retained from our more distant Hominoidea ancestors) primarily to allow high muscle-tendon power outputs, and indeed we remain relatively powerless compared to many other species. Instead, the majority of evidence suggests that such tendons evolved to reduce total locomotor energy cost. However, numerous additional, often unrecognised, advantages of long tendons may speculatively be of greater evolutionary advantage, including the reduced limb inertia afforded by shorter and lighter muscles (reducing proximal muscle force requirement), reduced energy dissipation during the foot-ground collisions, capacity to store and reuse the muscle work done to dampen the vibrations triggered by foot-ground collisions, reduced muscle heat production (and thus core temperature), and attenuation of work-induced muscle damage. Cumulatively, these effects should reduce both neuromotor fatigue and sense of locomotor effort, allowing humans to choose to move at faster speeds for longer. As these benefits are greater at faster locomotor speeds, they are consistent with the hypothesis that running gaits used by our ancestors may have exerted substantial evolutionary pressure on Achilles tendon length. The long Achilles tendon may therefore be a singular adaptation that provided numerous physiological, biomechanical, and psychological benefits and thus influenced behaviour across multiple tasks, both including and additional to locomotion. While energy cost may be a variable of interest in locomotor studies, future research should consider the broader range of factors influencing our movement capacity, including our decision to move over given distances at specific speeds, in order to understand more fully the effects of Achilles tendon function as well as changes in this function in response to physical activity, inactivity, disuse and disease, on movement performance.
... A study by Didehdar et al. [41] found a significant positive relationship between muscle temperature and vertical jump height. A study by Bergh et al. [47] reached similar conclusions, with a 4.2% increase/decrease in vertical jump height for every 1 °C increase/decrease in muscle temperature. ...
To compare the efficacy of different recovery strategies (sitting; cold water immersion, CWI; vibration foam rolling, VFR) on the lower extremities of amateur basketball players after the simulated load of a basketball game, we assessed the power, agility, and dynamic balance before and after interventions. Ten amateur basketball players alternately underwent 12 min of sitting, 12 min of CWI at 5 °C, and 12 min of VFR. The power, agility, and dynamic balance were measured immediately post-warm-up, immediately post-game, immediately post-intervention, 1 h after interventions , and 24 h after interventions. To simulate the load of a basketball game, specific movements were designed and implemented. Jump height was measured using a Kistler force plate. Reaction time and dynamic balance score were assessed using the Pavigym agility response system and the Y balance test, respectively. The data were analyzed with a two-way repeated measures analysis of variance (ANOVA). The results showed that the vertical jump height significantly decreased after the CWI intervention compared to the CON and VFR groups (p < 0.001). At 1 h after the intervention, the vertical jump height in the CON group showed delayed recovery compared to the CWI and VFR groups (p = 0.007; p < 0.001). At 24 h after the intervention, the vertical jump height in the CWI group further increased and was significantly different from the CON and VFR groups (p < 0.001; p = 0.005). Additionally, reaction times significantly increased immediately after the CWI intervention (p = 0.004) but showed further recovery at 24 h compared to the CON group (p < 0.001). The dynamic balance score significantly rebounded after the CWI intervention compared to the CON group (p = 0.021), with further improvement at 24 h (p < 0.001). CWI initially showed negative effects, but over time, its recovery effect was superior and more long-lasting. VFR had the best immediate effect on lower limb recovery after the game.
... Dies um fasst speziell die Freisetzung und Diffusion von Kalzium und Acetylcholin[35]. Die Muskelkraft hängt von der Mus keltemperatur ab, wobei die Abnahme der Muskeltempe ratur von 4 bis 6 % pro °C bis auf 30 °C reicht[36]. Bei Nerventemperaturen unter ~ 20 °C wird die Nervenleitung verlangsamt und die Amplitude des Aktionspotenzials ver ringert[37]. ...
Abstract: Just a few years ago, no one could imagine that ice swimming could evolve into a competitive sport. In the past, people swimming in ice-cold water were called madmen and, at best, were studied as scientific objects. Today regular competitions in ice swimming over different distances (ice mile, ice km, and shorter distances such as 50 m, 100 m, and 200 m), and different disciplines are organized (freestyle, breaststroke, backstroke, butterfly). National championships, as well as continental and world championships, are also held, with new records set regularly. In this overview, we summarize the historical development of ice swimming up to a competitive sport and explore the risks in this nascent sports discipline.
Zusammenfassung: Noch vor wenigen Jahren konnte sich niemand vorstellen, dass sich Eisschwimmen zu einem Wett-kampfsport entwickeln könnte. Früher wurden Menschen, die in eiskaltem Wasser geschwommen sind, als Verrückte bezeichnet und im günstigen Fall als wissenschaftliche Objekte untersucht. Heute gibt es mittlerweile offizielle Wettkämpfe für das Eis-bzw. Winterschwimmen über verschiedene kürzere Strecken (50 m, 100 m, 200 m, 1000 m) und Disziplinen (Freistil, Brustschwim-men, Rückenschwimmen, Delfin). Dabei werden auch Landesmeisterschaften bis hin zu Kontinental-und Weltmeisterschaften ausgetragen. Regelmässig werden neue Rekorde aufgestellt. In dieser Übersicht stellen wir die geschichtliche Entwicklung des Eisschwimmens bis hin zum Wettkampfsport zusammen und weisen auf die Risiken in dieser neuen Sportdisziplin hin.
... Asmussen & Boje (1945) and Bergh & Ekblom (1979) reported that the velocity dependent effect of muscle temperature on maximum external power to be ~ 4% higher in force and power per 1°C rise in quadriceps muscle temperature. Furthermore, per 1°C increase in muscle temperature, observed a 2-5% (Racinais & Oksa, 2010), and a 2-10% (Sargent, 1984) increase in peak power during exercise performance. ...
Prior to exercise, a warm-up routine has been suggested to be an imperative factor in task readiness with the anticipation that it will enhance performance. Key benefits of a warm-up are the increase of muscle and core temperature, which can be achieved in a variety of ways. An effective way to achieve improvements in core and muscle temperature is by performing an active warm up. However, lengthy transition periods between an active warm-up and exercise performance, is known to decline core and muscle temperature, thereby reducing performance capability. As such, methods are needed to assist athletes during transition periods, to maintain the benefits of a warm-up with the aim of optimising performance. Accordingly, the purpose of this review is to systematically analyse the evidence base that has investigated the use of passive heating to aide sporting performance when a transition period is experienced. A systematic review and meta-analysis were undertaken following relevant studies being identified using PudMed, Web of Science, and EBSCO. Studies investigating the effects of passive heating strategies during the transition period between an active warm-up and exercise performance were included. The quality of included studies was assessed by 2 independent reviewers using a modified version of the Physiotherapy Evidence Database scale. Seven studies, all high quality (mean = 7.6), reported sufficient data (quality score > 5) on the effects of passive heating strategies on exercise performance. Passive heating strategies used between an active warm-up and exercise, appear to work favourably in all studies which examined peak power output (ES = 0.54 [95% CI 0.17 to 0.91]), however, only a favourable trend was evident for time to completion of exercise performance (ES = 1.07 [95% CI -0.64 to 0.09]). However, such conclusions are only based upon a limited number of well-conducted, randomised, controlled trials. Therefore, more studies are needed to further determine the role passive warming, during the transition period, has on exercise performance. Furthermore, additional research is necessary to determine the optimum procedure for passive warm-up strategies, including environmental conditions, length of time to the wear a heated garment, garment temperature, and the placement of the heating elements embodied into the garment.
... Warm-up can also be passive, where subjects undergo passive interventions such as passive heating to elevate body temperature (Bishop, 2003a). The elevated muscle temperature was found to increase the ATP turnover and muscle fiber conduction velocity, improving the performance of vertical jump and power output of sprint cycling (Bergh and Ekblom, 1979;Gray et al., 2006). It is important to monitor the changes in body temperature to understand the effect of prior exercise on subsequent motor performance. ...
Priming exercises improve subsequent motor performance; however, their effectiveness may depend on the workload and involved body areas. The present study aimed to estimate the effects of leg and arm priming exercises performed at different intensities on maximal sprint cycling performance. Fourteen competitive male speed-skaters visited a lab eight times, where they underwent a body composition measurement, two V̇O2max measurements (leg and arm ergometers), and five sprint cycling sessions after different priming exercise conditions. The five priming exercise conditions included 10-minute rest (Control); 10-minute arm ergometer exercise at 20% V̇O2max (Arm 20%); 10-minute arm ergometer exercise at 70% V̇O2max (Arm 70%); 1-min maximal arm ergometer exercise at 140% V̇O2max (Arm 140%); and 10-min leg ergometer exercise at 70% V̇O2max (Leg 70%). Power outputs of 60-s maximal sprint cycling, blood lactate concentration, heart rate, muscle and skin surface temperature, and rating of perceived exertion were compared between the priming conditions at different measurement points. Our results showed that the Leg 70% was the optimal priming exercise among our experimental conditions. Priming exercise with the Arm 70% also tended to improve subsequent motor performance, while Arm 20% and Arm 140% did not. Mild elevation in blood lactate concentration by arm priming exercise may improve the performance of high-intensity exercise.
... A 37% reduction was observed in vertical jumps immediately when the objects underwent CWI (Didehdar and Sobhani, 2019). The jump height was discovered to decrease by 4.2% for every 1°C decrease in muscle temperature (Bergh & Ekblom, 1979). The reason is that cold muscles can result in lower nerve impulse frequency and longer relaxation time. ...
Cold water immersion (CWI) is very popular as a method reducing post-exercise muscle stiffness, eliminating fatigue, decreasing exercise-induced muscle damage (EIMD), and recovering sports performance. However, there are conflicting opinions as to whether CWI functions positively or negatively. The mechanisms of CWI are still not clear. In this systematic review, we used meta-analysis aims to examine the effect of CWI on fatigue recovery after high-intensity exercise and exercise performance. A total of 20 studies were retrieved and included from PubMed, PEDro and Elsevier databases in this review. Publication years of articles ranged from 2002 to 2022. In selected studies including randomized controlled trials (RCTs) and Crossover design (COD). Analyses of subjective indicators such as delayed-onset muscle soreness (DOMS) and ratings of perceived exertion (RPE), and objective indicators such as countermovement jump (CMJ) and blood plasma markers including creatine kinase(CK), lactate/lactate dehydrogenase(LDH), C-reactive protein(CRP), and IL-6 were performed. Pooled data showed as follows: CWI resulted in a significant decline in subjective characteristics (delayed-onset muscle soreness and perceived exertion at 0 h); CWI reduced countermovement jump(CMJ) significantly at 0 h, creatine kinase(CK) was lowered at 24 h, and lactate at 24 and 48 h. There was no evidence that CWI affects C-reactive protein(CRP) and IL-6 during a 48-h recovery period. Subgroup analysis revealed that different CWI sites and water temperatures have no effect on post-exercise fatigue recovery. Recommended athletes immersed in cold water immediately after exercise, which can effectively reduce muscle soreness and accelerate fatigue recovery.
... It has been reported that performing FR totaling 60 s, without any other additional warmup activities, resulted in no increase in muscle temperature or muscle contractility (tensiomyography) 12 . Although the current study did not investigate the mechanisms behind isolated FR, it is known that an increase in muscle temperature correlates positively with force production 29 . Therefore, it can be speculated that the duration of FR activity, performed in isolation, within the current study might not have been long enough to increase muscle temperature and enhance CMJ and SJ height. ...
Foam rolling (FR) durations totaling ≤60 seconds (s) per muscle are reported to acutely increase flexibility and vertical jump performance. However, limited research has investigated whether these benefits can outlast the inactive post-warmup preparatory period that typically separates warmups from the start of sporting competition. 11 male athletes (height 1.77 ± 0.09 m, body mass 78.0 ± 17.0 kg, age 22 ± 2 years) completed familiarization, followed by 3 experimental trials in a randomized and counterbalanced repeated measures crossover design. Trials commenced with 5 minutes (min) of jogging, before ankle dorsiflexion range of motion (ADF-ROM), sit and reach (S&R), countermovement jump (CMJ), and squat jump (SJ) baseline testing. Participants then sat inactively for 10 min (control) or performed lower extremity FR totaling either 30 (30 FR) or 60 s (60 FR) that targeted four agonist-antagonist leg muscles. Testing was then repeated before and after a simulated inactive 15 min post-warmup preparatory period to establish the acute and delayed effects of FR on performance. A two-way repeated measures analysis of variance was used to identify any significant interaction effects between conditions (30 FR, 60 FR, control) and timepoint (baseline, acute, delayed). No significant condition x timepoint interaction effect was detected for the ADF-ROM (f = 1.63, p = 0.19), S&R (f = 0.80, p = 0.54), CMJ ((f = 0.83, p = 0.99), or SJ (f = 0.66, p = 0.99). Therefore, FR totaling ≤60 s appears insufficient to enhance flexibility or vertical jump performance in male athletes.
... Thus, the torque decrease at 60 min post-exercise in SS would not be caused by the aforementioned factors (i.e., structural disruption of the sarcomere and impaired excitation-contraction coupling). A previous study showed that muscle strength was positively correlated with muscle temperature (Bergh and Ekblom, 1979). In addition, muscle temperature was also reported to be gradually decreased during a rest period of 60 min after completing one session of resistance exercise (Kenny et al. 2003). ...
PurposeA previous study revealed that resistance exercise with eccentric contraction and a wide range of motion (ROM) can acutely decrease muscle stiffness of a specific muscle. To explore further approaches to decrease the stiffness, we examined the acute changes in passive stiffness of the individual hamstring muscles after eccentric-only resistance exercise with different combinations of muscle lengths and exercise durations.Methods
Thirteen healthy young male participants performed three sessions of eccentric-only exercises that comprised stiff-leg deadlift with different muscle lengths and exercise durations (duration per repetition × the total number of repetitions) on separate days as follows: (1) short muscle lengths with a short duration (SS); (2) long muscle lengths with a short duration (LS); and (3) long muscle lengths with a long duration (LL). Maximal joint ROM, passive torque, shear modulus of each hamstring muscle, and maximal isometric torque of knee flexion were measured before, and at 3, 30, and 60 min after each session.ResultsThe shear modulus of the semimembranosus was significantly lower at 3 min post-exercise (129.8 ± 22.7 kPa) than at pre-exercise (140.5 ± 19.1 kPa, p < 0.01) in LL, but not in SS or LS. No significant differences were observed in the shear moduli of the biceps femoris long head or semitendinosus between pre-exercise and 3 min post-exercise in any session.Conclusion
The combination of long muscle lengths and a long duration during eccentric-only resistance exercise is important to immediately decrease the stiffness (shear modulus) of a specific muscle.
This study examined the effects of traditional and modern warm-up protocols on jumping performance in U-17 football players. Twenty male athletes (mean age: 16.25 ± 0.43 years) participated in a crossover design, completing both warm-up types on separate days. The traditional protocol included sport-specific dynamic drills, while the modern protocol used activation tools like foam rollers and resistance bands. After each 30-minute session and a 15-minute rest, jumping ability was measured via the Five-Repetition Jump Test (5JT). Results showed significantly higher average and best jump heights following the traditional warm-up (p < 0.001), suggesting superior neuromuscular activation. These findings indicate that conventional dynamic warm-ups are more effective in enhancing explosive performance. While modern protocols may aid in proprioception and injury prevention, they appear less beneficial for immediate power output. Coaches are encouraged to consider integrating both methods to optimize pre-match preparation.
In this chapter, we will first provide an overview of human thermoregulatory response for maintaining core body temperature in cold environments, with some recent updates especially in the role of human brown adipose tissue (BAT) as a thermoeffector. The focuses on the inter- and intra-individual variation in the BAT activity and multiorgan contributions to cold-induced thermogenesis including shivering and nonshivering thermogenesis (NST) would be an original part. Mechanisms of cold-induced vasoconstriction are briefly summarized including the role of arterio-venous anastomoses (AVA), activation of the adrenergic neural function, and inhibition of nitric oxide vasodilator pathway. In addition, cold-induced vasodilation (CIVD), the paradoxical vasodilation response during cold immersion of distal extremities, is summarized with some recent updates in the potential physiological mechanism. The most important suggestion based on the laboratory studies is that a repeated cold exposure does not enhance CIVD response. Furthermore, as a physiological reaction other than thermoregulation, initial cold shock response at the onset of cold water immersion is summarized including the potential mechanism and habituation of the response. Next, regarding cold adaptation, categorization of cold acclimatization/acclimation into habituation of shivering, metabolic and insulative adaptation are summarized with some recent updates especially in the metabolic acclimation with enhanced NST and BAT activity. At the latter part of this chapter, we summarize physical performance impairment in cold environments such as maximal muscle strength, anaerobic power, endurance of submaximal exercise, and manual dexterities, with introducing potential underlying physiological mechanisms including thermoregulatory, neuromuscular, cardiovascular, and metabolic systems. Then, we introduce our recent studies on the greater contribution of anaerobic metabolism during submaximal exercise in cold and new training method with hypothermic skeletal muscle. Training in cold water utilizes the cold-induced physiological strain as an extra physiological load such as greater glycolytic metabolism even at low to moderate mechanical intensity. Our recent intervention study revealed that the hypothermic skeletal muscle training improves anaerobic power, even when moderate workload was repeated during the training session. Finally, we will introduce studies on cognitive performance in cold environments.
Cold weather can have deleterious effects on health, tolerance, and performance. This paper will review the physiological responses and external factors that impact cold tolerance and physical performance. Tolerance is defined as the ability to withstand cold stress with minimal changes in physiological strain. Physiological and pathophysiological responses to short‐term (cold shock) and long‐term cold water and air exposure are presented. Factors (habituation, anthropometry, sex, race, and fitness) that influence cold tolerance are also reviewed. The impact of cold exposure on physical performance, especially aerobic performance, has not been thoroughly studied. The few studies that have been done suggest that aerobic performance is degraded in cold environments. Potential physiological mechanisms (decreases in deep body and muscle temperature, cardiovascular, and metabolism) are discussed. Likewise, strength and power are also degraded during cold exposure, primarily through a decline in muscle temperature. The review also discusses the concept of thermoregulatory fatigue, a reduction in the thermal effector responses of shivering and vasoconstriction, as a result of multistressor factors, including exhaustive exercise. © 2016 American Physiological Society. Compr Physiol 6:443‐469, 2016.
Introduction: Warm-up is essential for optimizing athletic performance in both individual and team sports, though its effects tend to diminish or disappear after a certain period of time. However, in soccer, competition rules mandate a 15-min transition period before the match begins. Purpose: This study investigated the effect of this transitional period on maintaining performance in various physical abilities, including hip flexion range of motion (ROM), countermovement jump (CMJ),10 m and 30 m sprint speed, change of direction (COD) speed (measured via the Arrowhead Agility Test (AAT) for both directions: AATR for right and AATL for left), and repeated sprint ability (RSA). Method: Sixteen male semi-professional soccer players participated in the study, performing either a 25-min traditional warm-up (FIELD WU) or a 22-min pre-warm-up exercise program combined with the traditional soccer warm-up (GYM+FIELD WU). Results: A two-factor mixed ANOVA analysis ("program" and "time") revealed a significant interaction between the two factors only for the variables of ROM (p < 0.001) and CMJ (p < 0.02). Additionally, a significant decline in CMJ performance and a tendency toward reduced AATR performance were observed 15 min after completing the GYM+FIELD WU. Similarly, a significant decrease in ROM and AATL, along with a trend toward reduced 30 m sprint performance, was noted following the FIELD WU program in the same time frame. Conclusion: The results of this study indicate that the 15-min transitional period following the completion of both the FIELD WU and GYM+FIELD WU has a detrimental effect on the performance of soccer players.
Artistik Cimnastik - Germe Isınma Protokolü- Pliometrik Isınma- PNF Isınma
A growing body of data suggests that skeletal muscle contractile function and glucose metabolism vary by time-of-day, with chronobiological effects on intrinsic skeletal muscle properties being proposed as the underlying mediator. However, no studies have directly investigated intrinsic contractile function or glucose metabolism in skeletal muscle over a 24 h circadian cycle. To address this, we assessed intrinsic contractile function and endurance, as well as contraction-stimulated glucose uptake, in isolated extensor digitorum longus and soleus from mice at four times-of-day (zeitgeber times 1, 7, 13, 19). Significantly, though both muscles demonstrated circadian-related changes in gene expression, there were no differences between the four time points in intrinsic contractile function, endurance, and contraction-stimulated glucose uptake, regardless of sex. Overall, these results suggest that time-of-day variation in exercise performance and the glycemia-reducing benefits of exercise are not due to chronobiological effects on intrinsic muscle function or contraction-stimulated glucose uptake.
Human motion capture technology is utilized in many industries, including entertainment, sports, medicine, augmented reality, virtual reality, and robotics. However, motion capture data only allows the user to analyze human movement at a kinematic level. In order to study the corresponding dynamics and muscle properties, additional sensors such as force plates and electromyography sensors are needed to collect the relevant data. Collecting, processing, and synchronizing data from multiple sources could be laborious and time-consuming. This study proposes a method to generate the dynamics and muscle properties of existing motion capture datasets. To do so, our method reconstructs motions via kinematics, dynamics, and muscle modeling with a musculoskeletal model consisting of 14 joints, 40 degrees of freedom, and 15 segments. Compared to current physics simulators, our method also infers muscle properties to ensure our human model is realistic. We have met International Society of Biomechanics standards for all terminologies and representations. Furthermore, our integrated musculoskeletal model allows the user to preselect various anthropometric features of the human performing the motion, such as height, mass, level of athleticism, handedness, and skin temperature, which are often infeasible to estimate from monocular videos without appropriate annotations. We apply our method on the Human3.6M dataset and show that our reconstructed motion is kinematically similar to the ground truth markers while being dynamically plausible when compared to experimental data found in literature. The generated data (Human3.6M+) is available for download.
Background: Whilst muscle contractility increases with muscle temperature, there is no consensus on the best warm-up protocol to use before resistance training or sports exercise due to the range of possible warm-up and testing combinations available. Objectives: To determine the effects of different warm-up types (active, exercise-based vs. passive) on muscle function tested using different activation methods (voluntary vs. evoked) and performance test criteria (maximum force vs. rate-dependent contractile properties), with consideration of warm-up task specificity (specific vs. non-specific), temperature measurement sites (muscle vs. skin), baseline temperatures, and subject-specific variables (training status and sex). Methods: A systematic search was conducted on 6 electronic databases. Random-effects meta-analyses and meta-regressions were used to compute the effect sizes (ES±95% confidence intervals) to examine the effects of warm-up type, activation method, performance criterion, subject characteristics, and study design on temperature-related performance enhancement. Results: The search yielded 1272 articles, of which 33 met the inclusion criteria (n=921). Increasing temperature positively affected both voluntary (3.7±1.8%/°C, ES=0.28 [0.14, 0.41]) and evoked (3.2±1.5%/°C, ES=0.65 [0.29, 1.00]) rate-dependent contractile properties (dynamic, fast-velocity force production and rate of force development [RFD]) but not maximum force production (voluntary: - 0.2±0.9%/°C, ES=0.08 [-0.05, 0.22]; evoked: -0.1±0.8%/°C, ES=-0.20 [-0.50, 0.10]). Active warm-up did not induce greater enhancements in rate-dependent contractile properties (p=0.284), maximum force production (p=0.723), or overall function (pooled, p=0.093) than passive warm-up. Meta-regressions did not reveal a significant effect of study design, temperature measurement site, warm-up task specificity, training status, or sex on the effect of increasing temperature (p>0.05). Conclusion: Increasing muscle temperature significantly enhances rate-dependent contractile function (RFD and muscle power) but not maximum force in both evoked and voluntary contractions. In contrast to expectation, no effects of warm-up modality (active vs. passive), study design (full data vs. no control), or temperature measurement site (muscle vs. skin) were detected, although a lack of data prevented robust subgroup analysis. Future research should further investigate the effect of increasing temperature on muscle function using well-designed and well-controlled study designs (i.e., randomized controlled trials).
We examined the effects of substitution time (i.e., recovery time) in a simulated field hockey test on physical, technical and perceptual/cognitive performance. Nine sub-elite male field hockey players (age: 20 ± 2 yrs, height: 1.81 ± 0.06 m, body mass: 71 ± 10 kg, body fat: 10.3 ± 3.7%, V̇O2max: 67 ± 3 mL·kg-1·min-1) completed four 8-min 40-s bouts of high-intensity intermittent exercise with 2-min and 5.5-min substitution time replicating the demands of a 4-quarter field hockey match. After each bout, a 15-m maximal sprint, agility/dribbling test, passing accuracy test, and a cognitive task were completed. Heart rate (p < .001) and rating of perceived exertion (RPE) (p < .001) increased with every bout. RPE was higher for the 5.5-min condition during the 2nd and 4th bout. No differences were observed between the substitution times and the number of bouts on 15-m maximal sprint time (2-min: 2.03 ± 0.14 s, 5.5-min: 2.07 ± 0.12 s), average reaction time (2-min: 347.19 ± 30.78 ms, 5.5-min: 346.69 ± 38.73 ms), cognitive error rate (2-min: 0.86 ± 0.77; 5.5-min: 0.44 ± 0.37), passing accuracy (2-min: 6 ± 1, 5.5-min: 6 ± 1) and agility/dribbling time (2-min: 7.06 ± 0.41 s, 5.5-min: 7.23 ± 0.55 s). It was concluded that a longer recovery time (i.e., substitution time 5.5-min) did not provide better physical and technical performance than 2-min during a simulated 4-quarter field hockey test. Further research with a larger sample size should address whether the shorter 2-min substitution time seemed to result in lower cognitive performance.
Context:
Melatonin is an ancient molecule with a wide range of functions in mammals, such as antioxidant, anti-inflammatory, and hypothermic effects among others. However, the influence of acute melatonin administration on human physical performance is debatable.
Objective:
To summarize available data from controlled trials about the effects of acute melatonin administration on human physical performance, especially with respect to strength, power, speed, and short- and long-term continuous exercise.
Data sources:
A systematic search of the PubMed, Web of Science, Scopus, Embase, and Cochrane databases up to December 10, 2021, was conducted using specified keywords and Boolean operators ("melatonin" AND "exercise OR circuit-based exercise OR plyometric exercise OR exercise tolerance OR exercise test").
Study selection:
Only controlled studies in the English language and with humans were accepted.
Study design:
Systematic review.
Level of evidence:
Level 1.
Data extraction:
Participants' characteristics (sex, age, body mass, height and fat percentage), melatonin dose and administration time, and outcomes from the performance trial were extracted.
Results:
A total of 10 studies were identified after the screening process. Overall, melatonin did not change speed or short-term continuous exercise performances. However, in relation to strength and power, the results are debatable since 5 articles showed no difference, while another 2 pointed to a decrease in performance. In terms of performance improvement, only 1 study reported an increase in balance and another in long-term continuous exercise performance in nonathletes, with no advantage found for athletes.
Conclusion:
Melatonin did not cause any significant change in strength, speed, power, and short-term continuous exercise performances. In fact, it led to reduced strength and power performances in specific tests. On the other hand, melatonin seems to have improved balance and long-term continuous exercise performance, at least in nonathletes. More investigations are required to corroborate these findings.
1. Influence of temperature (range 20-35 degrees C) on the isometric contractile properties of normal and chronically denervated fast-twitch extensor digitorum longus and slow-twitch soleus muscles of the rat have been studied in vitro. 2. The times to peak twitch tension of denervated muscles were longer than those of normal in both types of muscle. The denervated muscles were, however, identifiable as 'fast-twitch' or 'slow-twitch' throughout the entire temperature range. 3. The twitch tension/tetanic tension ratios of the denervated muscles at 35 degrees C were significantly higher than those of the normal muscles. 4. The twitch tension of the normal extensor digitorum longus muscles increased whereas that of the normal soleus muscles decreased with cooling from 35 to 20 degrees C. Such a qualitative difference did not exist between the denervated extensor digitorum longus and soleus muscles. The twitch tensions of both denervated muscles decreased with cooling. 5. Cooling to 20 degrees C resulted in a greater fall in tetanic tension in the denervated than in the normal muscles.
Changes in extremity temperatures during general cold stress were investigated. The changes in local temperatures were found equal to those seen under circulatory arrest. In order to investigate the influence of these changes on motor function, the relation between local temperature and nervous conduction velocity in a peripheral motor nerve (n. ulnaris) was carried out in subjects exposed to a minor cold stress (to aboid the influence of Lewis hunting reaction). The decrease in conduction velocity was found to be 15 m/s per 10 degrees C fall in temperature. At a local temperature of 8-10 degrees C a complete nervous block was established. This leads to an explanation of the clinical findings in wet-cold situations, where the very rapid onset of physical impairment corresponds to the effect of a local cooling in the extremities and not, as commonly accepted, to a developing general hypothermia.
5 normal healthy male subjects were made hypothermic by allowing them to swim at a speed of 0.55 m/s (V(O2) about 50% of V(O2) max) for 30 min (until rectal temperature of approximately 35°C was reached) in a swimming flume containing water at 18°C. Immediately after the end of the swim the response to submaximal and maximal exercise on an arm and leg bicycle ergometer under standardized laboratory conditions with and without atropine (2 mg i.v.) was measured and the data collected were compared to results obtained during normal cycling. In addition one subject was also studied after β blockade with propranolol (10 mg i.v.). The results show that following hypothermia V(E) and V(O2) at a given submaximal work load of 100 W increased (p<0.05) whereas the heart rate was reduced by 14 beats/min. Atropine reversed this latter change but was without effect on the observed increase in the metabolic cost of work. In contrast the administration of propranolol did not further reduce HR during submaximal exercise in hypothermia. At maximal effort hypothermia significantly reduced V(E)max, V(O2)max and HR max by 25 1/min, 0.42 1/min and 26 beats/min respectively. These changes were unaffected by atropine. The results from this study suggest that hypothermia may have a direct effect on the cardiac muscle and possibly that the β receptor activity is reduced by hypothermia.
It is a well established fact that the body temperature increases during muscular exercise, and that the increase is regulated (NIELSEN, 1938). It was the purpose of this paper to study the effect of the increased body temperature on the performance of maximum work, viz. a work performance of short duration (12 to 15 seconds) and a work performance lasting 4 to 5 minutes. The effect on a peak effort (a “push” or a “pull”) was also studied.
The experiments showed:
A given amount of work could be performed better – i. e. in a shorter time – when the organism was warmed up by a preliminary work. Also a greater muscular tension could be developed when “warmed up” than when not.
A passive warming up – e. g. by means of radio diathermy or by hot baths – also increased the capacity for work.
Massage had no beneficial effect on the performance.
The harder the preliminary work was, the higher rose the temperature and the better was the performance (only demonstrated in the work of shorter duration (12 to 15 sec.)).
The increased ability to perform hard work is closely correlated to the temperature of the working muscles.
The maximum oxygen uptake is slightly higher when the organism is warmed up than when this is not the case, but the oxygen necessary for a certain amount of work is reduced.
From these results it is concluded that a higher temperature in the muscles benefits the ability to perform work by accelerating the chemical processes in the muscles, probably also by decreasing the intramuscular viscous resistance. The accurately regulated higher rectal temperature in work (NIELSEN) allows the muscles to obtain a higher temperature during work than would otherwise be possible.
The force-velocity relationship of maximal contractions with the handgrip muscles is established in a group of subjects. The effect of different muscle temperatures is studied. The parameters vo (maximal velocity), Fo (maximal force), Pmax (maximal power), a/Fo and H (both parameters describing the shape of the curve), and Ft/Fo (the value of the force at which power is maximal) are established. It is shown that 1) in repeated measurements the coefficient of variation in general is less than 10% for all the parameters except a/Fo; 2) the parameter a/Fo should be discarded in comparative measurements since it is not linearly related to the course of the curve. A parameter called H should be used instead to describe the curvature; 3) an increase in muscle temperature is accompanied by an increase in magnitude of all parameters except Fo. The temperature effect expressed as Q10 in the range 22-38 degrees C is in the order of 1.2.
Standardized measurements of dynamic strength of the kneee extensor muscles were performed in 25 healthy male subjects (17-37 yr) by means of isokinetic contractions, i.e., knee extensions with constant angular velocities. Overall variation between double determinations of maximal torque throughout the 90 degrees arc of motion (0 degrees = fully extended leg) averaged 10% for the different constant velocities chosen. At any given angle of the knee the torque produced was higher for isometric than for dynamic contractions. Dynamic torque decreased gradually with increased speed of shortening. Peak dynamic torque was reached at knee angles in the range: 55-66 degrees, with a displacement toward smaller knee angles with higher angular velocities. Correlations were demonstrated between peak torque produced at the highest speed of muscle shortening and percent as well as relative area of fast twitch fibers in the contracting muscle. In addition muscles with a high percentage of fast twitch fibers had the highest maximal contraction speeds. These observations on intact human skeletal muscle are consistent with earlier findings in animal skeletal muscle preparations.
The effect of changes in the muscle temperature on their ability to store elastic energy was studied by having 5 trained subjects perform maximal vertical jumps on a force platform, with and without counter movement, at muscle temperatures between about 32 degrees C and 37 degrees C. The results showed that the heights of vertical jumps were considerably reduced at lowered temperature, but the gain in height after a counter movement in the form of a jump down from a height of 0.4 m over the force platform, was significantly higher in the cold condition. T o test whether this was due to an increased stiffness of the muscles, experiments with imposed sinusoidal length variations at 14 Hz were performed. Delta force XDelta length-1 (i.e.stiffness) increased with isometric tension independent of muscle temperature. Experiments in which the rate of tension development and relaxation in voluntary maximal isometric contractions were measured at different muscle temperatures showed that maximal isometric tension changed by less than 1% per degree but the rate of tension development and relaxation by 3-5% and 5% per degree, respectively, in the temperature range studied (30 degrees to 40 degrees). These data may be explained by the hypothesis that the series elastic components of the active muscle are located in the cross-bridges between myosin and actin filaments. The storage of elastic energy would be enhanced if the rate of breaking of these bridges were decreased at lower temperatures.
Cross-reinnervation of slow and fast muscles increases the contraction velocity of slow muscles and decreases that of fast ones. It, therefore, appears that the innervation regulates this physiological property of muscle. If actomyosin ATPase activity is, indeed, rate-limiting in the sequence of chemical events mediating contraction velocity, a comparison of the properties of this enzyme from slow and fast muscles should help elucidate the neural regulatory mechanism. Actomyosin, isolated from fast muscle of the cat, had threefold greater ATPase activity and was relatively more alkali-stabile and acid-labile than was actomyosin from slow muscle. These differences were demonstrable histochemically. Fibers having high ATPase activity predominate in fast muscles and fibers having low ATPase activity predominate in slow ones. By exposing frozen sections to acid or alkali before staining for ATPase, it was shown that the high-ATPase fibers are alkali-stabile and acid-labile, whereas as low-ATPase fibers are acid-stabile and alkali-labile. In addition, the fibers having high-ATPase activity could be further subdivided. The large-diameter fibers that predominate in the superficial parts of fast muscle are inhibited by formaldehyde, whereas the small-diameter fibers found mainly in the deeper parts of fast muscle (and in slow muscle of some species) are not. Preliminary observations indicate that under the influence of a foreign nerve, some acid-stabile fibers are converted to alkali-stabile ones. We conclude, on the basis of pH stability, that there are at least two qualitatively distinct actomyosin ATPases, and suggest that the nerve regulates the type of enzyme found in the muscle fiber.
1. The effects of altered tissue temperature on muscle metabolism during successive isometric contractions, sustained to fatigue, have been studied in the quadriceps muscle of man by combining biochemical analyses of metabolites in needle biopsy samples with measurements of endurance time with a force of 2/3 maximum voluntary contraction. Fatigue and recovery were observed repeatedly in a series of seven contractions at intervals of 20 sec, following immersion of the test leg in water at 12, 26 or 44° C for 45 min. Muscle temperatures corresponding to these water temperatures were 22·5, 32·6 and 38·6° C respectively.
2. Increased levels of several glycolytic intermediates at rest in the heated muscle suggested an increased rate of glycolysis. ATP and phosphoryl creatine were lower at the end of the first contraction and the calculated rate of ATP utilization (including the contribution from anaerobic glycolysis) was highest in the heated nuscle.
3. Significantly shorter endurance times were found for the heated muscle. These could not be attributed to depletion of local energy resources in muscle. Fatigue may be due to a reduction in the rate of regeneration of ATP from anaerobic glycolysis below that needed to maintain the contraction force. Lower values for the ratio of fructose 1,6‐diphosphate: fructose 6‐phosphate at the end of contractions, particularly at the highest temperature, are compatible with the hypothesis that there is partial inhibition of the rate controlling enzyme phosphofructokinase, possibly due to the accumulation of hydrogen ions in muscle.
Three categories of phosphatase activity toward adenosine triphosphate at pH 9.4 have been isolated histochemically: (1) phosphatase which requires -SH groups; (2) phosphatase which is inhibited by -SH groups; and (3) phosphatase which is relatively indifferent to -SH groups. This enzymatic activity was demonstrated in thin (5 µ), unfixed, frozen sections.
True adenosine triphosphatase has been separated histochemically by virtue of its -SH dependence. It was demonstrated in cardiac and skeletal muscle fibers and in the mitochondria of the kidney tubules. The staining of these structures can be prevented by treatment with an -SH inhibitor, such as p-chloromercuribenzoate or salyrganic acid. Also their stainability can be restored by reversing the inhibition of the enzymes with -SH compounds, such as BAL or cysteine. There was no reaction of these particular structures when adenosine diphosphate or adenosine-5-phosphate was used, suggesting that under the conditions of this histochemical test only the terminal phosphate of adenosine triphosphate is removed. Phosphatase activity of the smooth muscle of the intestinal muscularis toward adenosine triphosphate differed from that of striated muscle in that it was less sensitive to p-chloromercuribenzoate.
Sulfhydryl compounds, such as BAL or cysteine, enhanced the staining of the above mentioned sites of true adenosine triphosphatase activity. On the other hand, these -SH compounds are powerful inhibitors of alkaline phosphatase activity, especially toward adenosine-5-phosphate. When adenosine triphosphate was the substrate, BAL prevented the staining of the brush borders of the kidney tubules and intestinal epithelium, thus suggesting the participation of alkaline phosphatase in the dephosphorylation of adenosine triphosphate. Furthermore, the staining of these brush borders was unaffected by the -SH inhibitors.
The strong phosphatase activity of endothelium and vascular smooth muscle toward adenosine triphosphate was seemingly indifferent to -SH groups, since the staining of these structures was not markedly influenced by -SH inhibitors or compounds. The nature of this staining has not been elucidated.
Comparisons of the localization of phosphatase activity toward adenosine triphosphate, -diphosphate or -5-phosphate were made in the ventricle, tongue, kidney, and duodenum. Differences in the localization of phosphatase activity toward adenosine triphosphate and adenosine-5-phosphate were also made in liver, lung, spleen, uterus, and aorta.
Uppvärmningens inverkan på löpprestationerna. (The influence of warm‐up on running performance
- HÖGBERG P.
Ergogenic aids and muscular performance
- H. B. FALLS
Physiological reactions to wet‐cold
- VANGAARD L.