The effect of head and neck per-cooling on neuromuscular fatigue following exercise in the heat

2020 ◽  
Vol 45 (11) ◽  
pp. 1238-1246
Author(s):  
Ralph Joseph Frederick Hills Gordon ◽  
Neale Anthony Tillin ◽  
Christopher James Tyler
Keyword(s):  
Head And Neck ◽  
Thermal Sensation ◽  
Thermal Strain ◽  
Central Fatigue ◽  
Peak Oxygen Uptake ◽  
Voluntary Contraction ◽  
Peak Force ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Neck Cooling

The effect of localised head and neck per-cooling on central and peripheral fatigue during high thermal strain was investigated. Fourteen participants cycled for 60 min at 50% peak oxygen uptake on 3 occasions: thermoneutral control (CON; 18 °C), hot (HOT; 35 °C), and HOT with head and neck cooling (HOTcooling). Maximal voluntary force (MVF) and central activation ratio (CAR) of the knee extensors were measured every 30 s during a sustained maximal voluntary contraction (MVC). Triplet peak force was measured following cycling, before and after the MVC. Rectal temperatures were higher in HOTcooling (39.2 ± 0.6 °C) and HOT (39.3 ± 0.5 °C) than CON (38.1 ± 0.3 °C; P < 0.05). Head and neck thermal sensation was similar in HOTcooling (4.2 ± 1.4) and CON (4.4 ± 0.9; P > 0.05) but lower than HOT (5.9 ± 1.5; P < 0.05). MVF and CAR were lower in HOT than CON throughout the MVC (P < 0.05). MVF and CAR were also lower in HOTcooling than CON at 5, 60, and 120 s, but similar at 30 and 90 s into the MVC (P > 0.05). Furthermore, they were greater in HOTcooling than HOT at 30 s, whilst triplet peak force was preserved in HOT after MVC. These results provide evidence that central fatigue following exercise in the heat is partially attenuated with head and neck cooling, which may be at the expense of greater peripheral fatigue. Novelty Central fatigue was greatest during hyperthermia. Head and neck cooling partially attenuated the greater central fatigue in the heat. Per-cooling led to more voluntary force production and more peripheral fatigue.

The influence of ice slushy on voluntary contraction force following exercise-induced hyperthermia

2014 ◽  
Vol 39 (7) ◽  
pp. 781-786 ◽  
Author(s):  
Catriona A. Burdon ◽  
Christopher S. Easthope ◽  
Nathan A. Johnson ◽  
Phillip G. Chapman ◽  
Helen O’Connor
Keyword(s):  
Muscle Activation ◽  
Force Production ◽  
Central Fatigue ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Central Component ◽  
Induced Hyperthermia ◽  
Exercise Induced

This study aimed to investigate the effect of exercise-induced hyperthermia on central fatigue and force decline in exercised and nonexercised muscles and whether ingestion of ice slushy (ICE) ameliorates fatigue. Eight participants (5 males, 3 females) completed 45 s maximal voluntary isometric contractions (MVIC) with elbow flexors and knee extensors at baseline and following an exercise-induced rectal temperature (Trec) of 39.3 ± 0.2 °C. Percutaneous electrical muscle stimulation was superimposed at 15, 30 and 44 s during MVICs to assess muscle activation. To increase Trec to 39.3 °C, participants cycled at 60% maximum power output for 42 ± 11 min in 40 °C and 50% relative humidity. Immediately prior to each MVIC, participants consumed 50 g of ICE (–1 °C) or thermoneutral drink (38 °C, CON) made from 7.4% carbohydrate beverage. Participants consumed water (19 °C) during exercise to prevent hypohydration. Voluntary muscle force production and activation in both muscle groups were unchanged at Trec 39.3 °C with ICE (knee extensors: 209 ± 152 N) versus CON (knee extensors: 255 ± 157 N, p = 0.19). At Trec 39.3 °C, quadriceps mean force (232 ± 151 N) decreased versus baseline (302 ± 180 N, p < 0.001) and mean voluntary activation was also decreased (by 15% ± 11%, p < 0.001). Elbow flexor mean force decreased from 179 ± 67 N to 148 ± 65 N when Trec was increased to 39.3 °C (p < 0.001) but mean voluntary activation was not reduced at 39.3 °C (5% ± 25%, p = 0.79). After exercise-induced hyperthermia, ICE had no effect on voluntary activation or force production; however, both were reduced from baseline in the exercised muscle group. Peripheral fatigue was greater than the central component and limited the ability of an intervention designed to alter central fatigue.

Electrically-induced quadriceps fatigue in the contralateral leg impairs ipsilateral knee extensors performance

2021 ◽  
Author(s):  
Fabio Giuseppe Laginestra ◽  
Markus Amann ◽  
Emine Kirmizi ◽  
Gaia Giuriato ◽  
Chiara Barbi ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Central Fatigue ◽  
Endurance Performance ◽  
Voluntary Exercise ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Motor Drive ◽  
Time To Exhaustion ◽  
Crossover Effect ◽  
The Impact

Muscle fatigue induced by voluntary exercise, which requires central motor drive, causes central fatigue that impairs endurance performance of a different, non-fatigued muscle. This study investigated the impact of quadriceps fatigue induced by electrically-induced (no central motor drive) contractions on single-leg knee-extension (KE) performance of the subsequently exercising ipsilateral quadriceps. On two separate occasions, eight males completed constant-load (85% of maximal power-output) KE exercise to exhaustion. In a counterbalanced manner, subjects performed the KE exercise with no pre-existing quadriceps fatigue in the contralateral leg on one day (No-PreF), while on the other day, the same KE exercise was repeated following electrically-induced quadriceps fatigue in the contralateral leg (PreF). Quadriceps fatigue was assessed by evaluating pre- to post-exercise changes in potentiated twitch force (ΔQtw,pot; peripheral-fatigue), and voluntary muscle activation (ΔVA; central-fatigue). As reflected by the 57±11% reduction in electrically-evoked pulse force, the electrically-induced fatigue protocol caused significant knee-extensors fatigue. KE endurance time to exhaustion was shorter during PreF compared to No-PreF (4.6±1.2 vs 7.7±2.4 min; p<0.01). While ΔQtw,pot was significantly larger in No-PreF compared to PreF (-60% vs -52%, p<0.05), ΔVA was greater in PreF (-14% vs -10%, p<0.05). Taken together, electrically-induced quadriceps fatigue in the contralateral leg limits KE endurance performance and the development of peripheral fatigue in the ipsilateral leg. These findings support the hypothesis that the crossover-effect of central fatigue is mainly mediated by group III/IV muscle afferent feedback and suggest that impairments associated with central motor drive may only play a minor role in this phenomenon.

scholarly journals Pre-Exercise Rehydration Attenuates Central Fatigability during 2-Min Maximum Voluntary Contraction in Hyperthermia

Medicina ◽  
2019 ◽  
Vol 55 (3) ◽  
pp. 66
Author(s):  
Kazys Vadopalas ◽  
Aivaras Ratkevičius ◽  
Albertas Skurvydas ◽  
Saulė Sipavičienė ◽  
Marius Brazaitis
Keyword(s):  
Body Weight ◽  
Physiological Stress ◽  
Maximum Voluntary Contraction ◽  
Thermal Strain ◽  
Plasma Osmolality ◽  
Voluntary Contraction ◽  
Whole Body ◽  
Knee Extensors ◽  
Lower Body ◽  
Whole Body Hyperthermia

Background and objectives: Hyperthermia with dehydration alters several brain structure volumes, mainly by changing plasma osmolality, thus strongly affecting neural functions (cognitive and motor). Here, we aimed to examine whether the prevention of significant dehydration caused by passively induced whole-body hyperthermia attenuates peripheral and/or central fatigability during a sustained 2-min isometric maximal voluntary contraction (MVC). Materials and Methods: Ten healthy and physically active adult men (21 ± 1 years of age) performed an isometric MVC of the knee extensors for 2 min (2-min MVC) under control (CON) conditions, after passive lower-body heating that induced severe whole-body hyperthermia (HT, Tre > 39 °C) with dehydration (HT-D) and after HT with rehydration (HT-RH). Results: In the HT-D trial, the subjects lost 0.94 ± 0.15 kg (1.33% ± 0.13%) of their body weight; in the HT-RH trial, their body weight increased by 0.1 ± 0.42 kg (0.1% ± 0.58%). After lower-body heating, the HT-RH trial (vs. HT-D trial) was accompanied by a significantly lower physiological stress index (6.77 ± 0.98 vs. 7.40 ± 1.46, respectively), heart rate (47.8 ± 9.8 vs. 60.8 ± 13.2 b min−1, respectively), and systolic blood pressure (−12.52 ± 5.1 vs. +2.3 ± 6.4, respectively). During 2-min MVC, hyperthermia (HT-D; HT-RH) resulted in greater central fatigability compared with the CON trial. The voluntary activation of exercising muscles was less depressed in the HT-RH trial compared with the HT-D trial. Over the exercise period, electrically (involuntary) induced torque decreased less in the HT-D trial than in the CON and HT-RH trials. Conclusions: Our results suggest that pre-exercise rehydration might have the immediate positive effect of reducing physiological thermal strain, thus attenuating central fatigability even when exercise is performed during severe (Tre > 39 °C) HT, induced by passive warming of the lower body.

scholarly journals Arterial Elasticity, Strength, Fatigue, and Endurance in Older Women

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Gary R. Hunter ◽  
William H. Neumeier ◽  
C. Scott Bickel ◽  
John P. McCarthy ◽  
Gordon Fisher ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Older Women ◽  
Central Fatigue ◽  
Ethnic Origin ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Large Artery ◽  
Arterial Elasticity ◽  
The Central Nervous System

Arterial health may influence muscle function in older adults. Study purpose was to determine whether arterial elasticity is related to strength, central and peripheral fatigue, fatigue at rest, and treadmill endurance. Subjects were 91 healthy women aged >60. Treadmill endurance and maximal oxygen uptake (VO2max) were measured. Peripheral and central fatigue for the knee extensors were evaluated using two isometric fatigue tests (one voluntary and one adding electrical stimulation). Arterial elasticity was determined using radial artery pulse wave analysis. Linear multiple regression was used in statistical analysis. Large artery elasticity was associated with central fatigue(P<0.01)and treadmill endurance(P<0.02)after adjusting for VO2max and knee extension strength. Subjective fatigue at rest was related to large artery elasticity after adjusting for ethnic origin (<0.02). Strength was significantly related to small artery elasticity after adjusting for ethnic origin, leg lean tissue, age, and blood pressure. Arterial elasticity is independently related to strength and fatigue in older women, especially in the central nervous system where arterial elasticity is independently related to perceptions of fatigue at rest and central fatigue. These results suggest that arterial health may be involved with the ability of the central nervous system to activate muscle in older women.

scholarly journals Hyperthermia and central fatigue during prolonged exercise in humans

2001 ◽  
Vol 91 (3) ◽  
pp. 1055-1060 ◽  
Author(s):  
Lars Nybo ◽  
Bodil Nielsen
Keyword(s):  
Core Temperature ◽  
Maximal Oxygen Consumption ◽  
Knee Extensor ◽  
Central Fatigue ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Total Force ◽  
Impaired Performance

The present study investigated the effects of hyperthermia on the contributions of central and peripheral factors to the development of neuromuscular fatigue. Fourteen men exercised at 60% maximal oxygen consumption on a cycle ergometer in hot (40°C; hyperthermia) and thermoneutral (18°C; control) environments. In hyperthermia, the core temperature increased throughout the exercise period and reached a peak value of 40.0 ± 0.1°C (mean ± SE) at exhaustion after 50 ± 3 min of exercise. In control, core temperature stabilized at ∼38.0 ± 0.1°C, and exercise was maintained for 1 h without exhausting the subjects. Immediately after the cycle trials, subjects performed 2 min of sustained maximal voluntary contraction (MVC) either with the exercised legs (knee extension) or with a “nonexercised” muscle group (handgrip). The degree of voluntary activation during sustained maximal knee extensions was assessed by superimposing electrical stimulation (EL) to nervus femoralis. Voluntary knee extensor force was similar during the first 5 s of contraction in hyperthermia and control. Thereafter, force declined in both trials, but the reduction in maximal voluntary force was more pronounced in the hyperthermic trial, and, from 30 to 120 s, the force was significantly lower in hyperthermia compared with control. Calculation of the voluntary activation percentage (MVC/MVC + EL) revealed that the degree of central activation was significantly lower in hyperthermia (54 ± 7%) compared with control (82 ± 6%). In contrast, total force of the knee extensors (MVC + force from EL) was not different in the two trials. Force development during handgrip contraction followed the same pattern of response as was observed for the knee extensors. In conclusion, these data demonstrate that the ability to generate force during a prolonged MVC is attenuated with hyperthermia, and the impaired performance is associated with a reduction in the voluntary activation percentage.

Exercising muscle mass influences neuromuscular, cardiorespiratory, and perceptual responses during and following ramp incremental cycling to task failure

2021 ◽  
Author(s):  
Jenny Zhang ◽  
Danilo Iannetta ◽  
Mohammed Alzeeby ◽  
Martin J. MacInnis ◽  
Saied Jalal Aboodarda
Keyword(s):  
Muscle Mass ◽  
Perceived Exertion ◽  
Central Fatigue ◽  
Exercise Duration ◽  
Peak Oxygen Uptake ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Peak Power Output ◽  
Task Failure ◽  
Single Twitch

Neuromuscular (NM), cardiorespiratory, and perceptual responses to maximal graded exercise using different amounts of active muscle mass remain unclear. We hypothesized that during dynamic exercise, peripheral NM fatigue (declined twitch force) and muscle pain would be greater using smaller muscle mass, whereas central fatigue (declined voluntary activation) and ventilatory variables would be greater using larger muscle mass. Twelve males (29.8±4.7 years) performed two cycling ramp incremental tests until task failure: (i) single-leg (SL) with 10 W·min-1ramp, and (ii) double-leg (DL) with 20 W·min-1ramp. NM fatigue was assessed at baseline, task failure (post), then after 1, 4, and 8 min of recovery. Cardiorespiratory and perceptual variables (i.e., ratings of perceived exertion (RPE), fatigue, pain, dyspnea) were measured throughout cycling. Exercise duration was similar between sessions (SL: 857.7±263.6; DL: 855.0±218.8 s; p=0.923) and higher absolute peak power output was attained in DL (SL: 163.2±43.8; DL: 307.0±72.0 W; p<0.001). While central fatigue did not differ between conditions (SL: -6.6±6.5%; DL: -3.5±4.8%; p=0.091), maximal voluntary contraction (SL: -41.6±10.9%; DL: -33.7±8.5%; p=0.032) and single twitch forces (SL: -59.4±18.8%; DL: -46.2±16.2%; p=0.003) declined more following SL. DL elicited higher peak oxygen uptake (SL: 42.1±10.0; DL:50.3±9.3 mL·kg-1·min-1; p<0.001), ventilation (SL: 137.1±38.1; DL: 171.5±33.2 L·min-1; p<0.001), and heart rate (SL: 167±21; DL: 187±8 bpm; p=0.005). Dyspnea (p=0.025) was higher in DL; however, RPE (p=0.005) and pain (p<0.001) were higher in SL. These results suggest that interplay between NM, cardiorespiratory, and perceptual determinants of exercise performance during incremental cycling to task failure are muscle mass-dependent.

scholarly journals Head Pre-Cooling Improves Symptoms of Heat-Sensitive Multiple Sclerosis Patients

2011 ◽  
Vol 38 (1) ◽  
pp. 106-111 ◽  
Author(s):  
Luke F. Reynolds ◽  
Christine A. Short ◽  
David A. Westwood ◽  
Stephen S. Cheung
Keyword(s):  
Multiple Sclerosis ◽  
Visual Acuity ◽  
Head And Neck ◽  
Thermal Sensation ◽  
Symptomatic Relief ◽  
Cooling Condition ◽  
Heat Sensitivity ◽  
Timed Up And Go ◽  
Multiple Sclerosis Patients ◽  
Neck Cooling

Abstract:Background:Damage to the central nervous system by Multiple Sclerosis (MS) leads to multiple symptoms, including weakness, ambulatory dysfunction, visual disturbances and fatigue. Heat can exacerbate the symptoms of MS whereas cooling can provide symptomatic relief. Since the head and neck areas are particularly sensitive to cold and cooling interventions, we investigated the effects of cooling the head and neck for 60 minutes on the symptoms of MS.Methods:We used a double blinded, placebo controlled, cross-over study design to evaluate the effects of head and neck cooling on six heat-sensitive, stable, ambulatory females with MS (Extended Disability Status Scale 2.5-6.5). To isolate the effects of perceived versus physiological cooling, a sham cooling condition was incorporated, where subjects perceived the sensation of being cooled without any actual physiological cooling. Participants visited the clinic three times for 60 minutes of true, sham, or no cooling using a custom head and neck cooling hood, followed by evaluation of ambulation, visual acuity, and muscle strength. Rectal and skin temperature, heart rate, and thermal sensation were measured throughout cooling and testing.Results:Both the true and sham cooling elicited significant sensations of thermal cooling, but only the true cooling condition decreased core temperature by 0.37°C (36.97±0.21 to 36.60±0.23°C). True cooling improved performance in the six minute walk test and the timed up-and-go test but not visual acuity or hand grip strength.Conclusions:Head and neck cooling may be an effective tool in increasing ambulatory capacity in individuals with MS and heat sensitivity.

Cycling performed on an innovative ergometer at different intensities–durations in men: neuromuscular fatigue and recovery kinetics

2019 ◽  
Vol 44 (12) ◽  
pp. 1320-1328 ◽  
Author(s):  
Renata L. Krüger ◽  
Saied Jalal Aboodarda ◽  
Libia Marcela Jaimes ◽  
Pierre Samozino ◽  
Guillaume Y. Millet
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Central Fatigue ◽  
Voluntary Activation ◽  
Moderate Intensity ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Accurate Estimation ◽  
Moderate Intensity Exercise ◽  
Mod P

The majority of studies have routinely measured neuromuscular (NM) fatigue with a delay (∼1–3 min) after cycling exercises. This is problematic since NM fatigue can massively recover within the first 1–2 min after exercise. This study investigated the etiology of knee extensors (KE) NM fatigue and recovery kinetics in response to cycling exercises by assessing NM function as early as 10 s following cycling and up to 8 min of recovery. Ten young males performed different cycling exercises on different days: a Wingate (WING), a 10-min task at severe-intensity (SEV), and a 90-min task at moderate-intensity (MOD). Electrically evoked and isometric maximal voluntary contractions (IMVC) of KE were assessed before, after, and during recovery. SEV induced the highest decrease in IMVC. Peak twitch (Pt) was more reduced in WING and SEV than in MOD (p < 0.001), whereas voluntary activation decreased more after MOD than WING (p = 0.043). Regarding Pt and the ratio between low- and high-frequency doublet (i.e., low-frequency fatigue), recovery was faster for WING, whereas IMVC and high-frequency doublet recovered slower during MOD (p < 0.05). Our results confirm that peripheral fatigue is greater after WING and SEV, while central fatigue is greater following MOD. Peripheral fatigue can substantially recover within minutes after a supramaximal exercise while NM function recovered slower after prolonged, moderate-intensity exercise. This study provides an accurate estimation of NM fatigue and recovery kinetics because of dynamic exercise with large muscle mass by significantly shortening the delay for postexercise measurements.

scholarly journals Neuromuscular Fatigue at Task Failure and During Immediate Recovery after Isometric Knee Extension Trials

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 156
Author(s):  
Christian Froyd ◽  
Fernando Beltrami ◽  
Timothy Noakes
Keyword(s):  
Femoral Nerve ◽  
Force Production ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Peak Force ◽  
Fatigue Threshold ◽  
Peripheral Fatigue ◽  
Neuromuscular Activation ◽  
Task Failure ◽  
Immediate Recovery

We asked whether the level of peripheral fatigue would differ when three consecutive exercise trials were completed to task failure, and whether there would be delayed recovery in maximal voluntary contraction (MVC) force, neuromuscular activation and peripheral fatigue following task failure. Ten trained sport students performed three consecutive knee extension isometric trials (T1, T2, T3) to task failure without breaks between trials. T1 and T2 consisted of repeated 5-s contractions followed by 5-s rests. In T1, contractions were performed at a target force at 60% pre-exercise MVC. In T2, all contractions were MVCs, and task failure occurred at 50% MVC. T3 was a sustained MVC performed until force fell below 15% MVC. Evoked force responses to supramaximal electrical femoral nerve stimulation were recorded to assess peripheral fatigue. Electromyography signals were normalized to an M-wave amplitude to assess neuromuscular activation. Lower levels of evoked peak forces were observed at T3 compared with T2 and T1. Within 5 s of task failure in T3, MVC force and neuromuscular activation recovered substantially without any recovery in evoked peak force. Neuromuscular activation 5–10 s after T3 was unchanged from pre-exercise values, however, evoked peak forces were substantially reduced. These results challenge the existence of a critical peripheral fatigue threshold that reduces neuromuscular activation. Since neuromuscular activation changed independently of any change in evoked peak force, immediate recovery in force production after exercise is due to increased central recruitment and not to peripheral mechanisms.

Central and Peripheral Fatigue in Sustained Maximum Voluntary Contractions of Human Quadriceps Muscle

1978 ◽  
Vol 54 (6) ◽  
pp. 609-614 ◽  
Author(s):  
B. Bigland-Ritchie ◽  
D. A. Jones ◽  
G. P. Hosking ◽  
R. H. T. Edwards
Keyword(s):  
Maximum Voluntary Contraction ◽  
Central Fatigue ◽  
Quadriceps Muscle ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Peripheral Fatigue ◽  
Emg Activity ◽  
Limiting Factor ◽  
Extra Effort ◽  
Voluntary Contractions

1. The fatigue of force that occurs during the first 60 s of a maximum voluntary contraction of the human quadriceps has been examined by comparing the voluntary force with that obtained by brief tetanic stimulation at 50 Hz in nine healthy subjects. In three subjects the voluntary force declined in parallel with the tetanic force whereas in the remainder it fell more rapidly, suggesting that central fatigue was present. 2. For those subjects who showed little or no central fatigue, surface electromyograph (EMG) activity remained approximately constant while the force declined by about 60%. In the others, EMG activity and force declined in parallel but when an extra effort was made the subjects could briefly increase their force and this was accompanied by a proportionately greater increase in EMG activity (generally up to the original value). 3. It is concluded that in sustained maximum voluntary contractions of the quadriceps (a) central fatigue may account for an appreciable proportion of the force loss, (b) surface EMG recordings provide no evidence that neuromuscular junction failure is the limiting factor determining the loss of force in this muscle.

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