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Respiratory Medicine Mar 2013Inspiratory muscle fatigue (IMF) may contribute to the development of exercise limitation and respiratory failure. Identifying fatigue of the inspiratory muscles... (Review)
Review
Inspiratory muscle fatigue (IMF) may contribute to the development of exercise limitation and respiratory failure. Identifying fatigue of the inspiratory muscles requires a rigorous and integrative methodological approach. However, there is no consensus about an optimal protocol to induce and assess the fatigability of the inspiratory muscles. A systematic review was performed to identify, evaluate, and summarize the literature related to the assessment of induced IMF in healthy individuals. The aim was to identify factors that are related consistently to IMF, as well as to suggest possible assessment methods. MEDLINE and EMBASE were searched for relevant articles until February 2012. Only studies with a quantitative description of assessment and outcome were included. The search yielded 460 citations and a total of 77 studies were included. Inspiratory muscle fatigue was produced acutely by inspiratory resistive loading (IRL), whole body exercise (WBE), hyperpnea, or WBE combined with IRL, and under normocapnic, hypoxic or hypercapnic conditions. To detect IMF, most studies (64%) used phrenic nerve stimulation, 44% used a maximal voluntary inspiratory maneuver and the remainder used electromyography. The heterogeneity of the published reports precluded a quantitative analysis. Inspiratory resistive loadings at intensities of 60-80% of maximum, and cycling at 85% of maximum were found to produce IMF most consistently. Hypoxic or hypercapnic conditions, and WBE combined with IRL, exacerbated IMF. The specific outcome measures employed to detect IMF, the magnitude of their change, as well as their functional significance, are ultimately dependent upon the research question being addressed.
Topics: Diaphragm; Electric Stimulation; Exercise Test; Humans; Muscle Fatigue; Phrenic Nerve; Respiratory Muscles
PubMed: 23273596
DOI: 10.1016/j.rmed.2012.11.019 -
PloS One 2023The rugby codes (i.e., rugby union, rugby league, rugby sevens [termed 'rugby']) are team-sports that impose multiple complex physical, perceptual, and technical demands...
The rugby codes (i.e., rugby union, rugby league, rugby sevens [termed 'rugby']) are team-sports that impose multiple complex physical, perceptual, and technical demands on players which leads to substantial player fatigue post-match. In the post-match period, fatigue manifests through multiple domains and negatively influences recovery. There is, however, currently no definition of fatigue contextualised to the unique characteristics of rugby (e.g., locomotor and collision loads). Similarly, the methods and metrics which practitioners consider when quantifying the components of post-match fatigue and subsequent recovery are not known. The aims of this study were to develop a definition of fatigue in rugby, to determine agreement with this common definition of fatigue, and to outline which methods and metrics are considered important and feasible to implement to quantify post-match fatigue. Subject matter experts (SME) undertook a two-round online Delphi questionnaire (round one; n = 42, round two; n = 23). SME responses in round one were analysed to derive a definition of fatigue, which after discussion and agreement by the investigators, obtained 96% agreement in round two. The SME agreed that fatigue in rugby refers to a reduction in performance-related task ability which is underpinned by time-dependent negative changes within and between cognitive, neuromuscular, perceptual, physiological, emotional, and technical/tactical domains. Further, there were 33 items in the neuromuscular performance, cardio-autonomic, or self-report domains achieved consensus for importance and/or feasibility to implement. Highly rated methods and metrics included countermovement jump force/power (neuromuscular performance), heart rate variability (cardio-autonomic measures), and soreness, mood, stress, and sleep quality (self-reported assessments). A monitoring system including highly-rated fatigue monitoring objective and subjective methods and metrics in rugby is presented. Practical recommendations of objective and subjective measures, and broader considerations for testing and analysing the resulting data in relation to monitoring fatigue are provided.
Topics: Humans; Athletic Performance; Football; Fatigue; Muscle Fatigue; Team Sports
PubMed: 36897849
DOI: 10.1371/journal.pone.0282390 -
Sensors (Basel, Switzerland) Feb 2022The objective detection of muscle fatigue reports the moment at which a muscle fails to sustain the required force. Such a detection prevents any further injury to the...
The objective detection of muscle fatigue reports the moment at which a muscle fails to sustain the required force. Such a detection prevents any further injury to the muscle following fatigue. However, the objective detection of muscle fatigue still requires further investigation. This paper presents an algorithm that employs a new fatigue index for the objective detection of muscle fatigue using a double-step binary classifier. The proposed algorithm involves analyzing the acquired sEMG signals in both the time and frequency domains in a double-step investigation. The first step involves calculating the value of the integrated EMG (IEMG) to determine the continuous contraction of the muscle being investigated. It was found that the IEMG value continued to increase with prolonged muscle contraction and progressive fatigue. The second step involves differentiating between the high-frequency components (HFC) and low-frequency components (LFC) of the EMG, and calculating the fatigue index. Basically, the segmented EMG signal was filtered by two band-pass filters separately to produce two sub-signals, namely, a high-frequency sub-signal (HFSS) and a low-frequency sub-signal (LFSS). Then, the instantaneous mean amplitude (IMA) was calculated for the two sub-signals. The proposed algorithm indicates that the IMA of the HFSS tends to decrease during muscle fatigue, while the IMA of the LFSS tends to increase. The fatigue index represents the difference between the IMA values of the LFSS and HFSS, respectively. Muscle fatigue was found to be present and was objectively detected when the value of the proposed fatigue index was equal to or greater than zero. The proposed algorithm was tested on 75 EMG signals that were extracted from 75 middle deltoid muscles. The results show that the proposed algorithm had an accuracy of 94.66% in distinguishing between conditions of muscle fatigue and non-fatigue.
Topics: Algorithms; Electromyography; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal
PubMed: 35271046
DOI: 10.3390/s22051900 -
Scandinavian Journal of Medicine &... Oct 2022This study compared the acute responses of three neuromuscular electrical stimulation (NMES) methods on muscle torque-time integral (TTI) and neuromuscular fatigue....
This study compared the acute responses of three neuromuscular electrical stimulation (NMES) methods on muscle torque-time integral (TTI) and neuromuscular fatigue. Narrow-pulse (0.2 ms; NP), wide-pulse (1 ms; WP), and tendon vibration superimposed onto wide-pulse (WP + VIB)-NMES conditions were applied to sixteen healthy individuals (n = 16) in three separate sessions in a randomized order. Stimulation intensity was set to elicit 20% of maximal voluntary contraction (MVC); the stimulus pattern comprised four sets of 20 repetitions (5 s On and 5 s Off) with a one-minute inter-set interval. TTI was measured for each NMES condition and MVC, voluntary activation (VA), peak twitch torque (Peak ), and peak soleus (EMG ), medial (EMG ), and lateral gastrocnemius (EMG ) electromyography were measured before and immediately after each NMES condition. TTI was higher during WP + VIB (19.63 ± 6.34 MVC.s, mean difference = 3.66, p < 0.001, Cohen's d = 0.501) than during WP (15.97 ± 4.79 MVC.s) condition. TTI was higher during WP + VIB (mean difference = 3.79, p < 0.001, Cohen's d = 0.626) than during NP (15.84 ± 3.73 MVC.s) condition. MVC and Peak forces decreased (p ≤ 0.001) immediately after all conditions. No changes were observed for VA (p = 0.365). EMG amplitude reduced (p = 0.040) only after NP, yet EMG and EMG amplitudes decreased immediately after all conditions (p = 0.003 and p = 0.013, respectively). WP + VIB produced a higher TTI than WP and NP-NMES, with similar amounts of neuromuscular fatigue across protocols. All NMES protocols induced similar amounts of peripheral fatigue and reduced EMG amplitudes.
Topics: Electric Stimulation; Electromyography; Humans; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Torque
PubMed: 35844045
DOI: 10.1111/sms.14210 -
Experimental Physiology Mar 2023What is the central question of this study? What are the physiological mechanisms underlying muscle fatigue and the increase in the O cost per unit of work during...
NEW FINDINGS
What is the central question of this study? What are the physiological mechanisms underlying muscle fatigue and the increase in the O cost per unit of work during high-intensity exercise? What is the main finding and its importance? Muscle fatigue happens before, and does not explain, the slow component ( ), but they share the same origin. Muscle activation heterogeneity is associated with muscle fatigue and . Knowing this may improve training prescriptions for healthy people leading to improved public health outcomes.
ABSTRACT
This study aimed to explain the slow component ( ) and muscle fatigue during cycling at different intensities. The muscle fatigue of 16 participants was determined through maximal isokinetic effort lasting 3 s during constant work rate bouts of moderate (MOD), heavy (HVY) and very heavy intensity (VHI) exercise. Breath-by-breath , near-infrared spectroscopy signals and EMG activity were analysed (thigh muscles). was higher during VHI exercise (∼70% vs. ∼28% of reserve in HVY). The deoxygenated haemoglobin final value during VHI exercise was higher than during HVY and MOD exercise (∼90% of HHb physiological normalization, vs. ∼82% HVY and ∼45% MOD). The muscle fatigue was greater after VHI exercise (∼22% vs. HVY ∼5%). There was no muscle fatigue after MOD exercise. The greatest magnitude of muscle fatigue occurred within 2 min (VHI ∼17%; HVY ∼9%), after which it stabilized. No significant relationship between and muscle force production was observed. The τ of muscle was significantly related (R = 0.47) with torque decrease for VHI. Type I and II muscle fibre recruitment mainly in the rectus femoris moderately explained the muscle fatigue (R = 0.30 and 0.31, respectively) and the (R = 0.39 and 0.27, respectively). The is also partially explained by blood lactate accumulation (R = 0.42). In conclusion muscle fatigue and O cost seem to share the same physiological cause linked with a decrease in the muscle and a change in lactate accumulation. Muscle fatigue and are associated with muscle activation heterogeneity and metabolism of different muscles activated during cycling.
Topics: Humans; Oxygen; Muscle, Skeletal; Muscle Fatigue; Energy Metabolism; Lactates; Oxygen Consumption
PubMed: 36648072
DOI: 10.1113/EP090444 -
Physiological Reports Nov 2023We evaluated whether task-dependent, age-related differences in muscle fatigue (contraction-induced decline in normalized power) develop from differences in...
We evaluated whether task-dependent, age-related differences in muscle fatigue (contraction-induced decline in normalized power) develop from differences in bioenergetics or metabolic economy (ME; mass-normalized work/mM ATP). We used magnetic resonance spectroscopy to quantify intracellular metabolites in vastus lateralis muscle of 10 young and 10 older adults during two maximal-effort, 4-min isotonic (20% maximal torque) and isokinetic (120°s ) contraction protocols. Fatigue, inorganic phosphate (Pi), and pH (p ≥ 0.213) differed by age during isotonic contractions. However, older had less fatigue (p ≤ 0.011) and metabolic perturbation (lower [Pi], greater pH; p ≤ 0.031) than young during isokinetic contractions. ME was lower in older than young during isotonic contractions (p ≤ 0.003), but not associated with fatigue in either protocol or group. Rather, fatigue during both tasks was linearly related to changes in [H ], in both groups. The slope of fatigue versus [H ] was 50% lower in older than young during isokinetic contractions (p ≤ 0.023), consistent with less fatigue in older during this protocol. Overall, regardless of age or task type, acidosis, but not ME, was the primary mechanism for fatigue in vivo. The source of the age-related differences in contraction-induced acidosis in vivo remains to be determined, as does the apparent task-dependent difference in the sensitivity of muscle to [H ].
Topics: Humans; Aged; Muscle Fatigue; Muscle, Skeletal; Aging; Isometric Contraction; Energy Metabolism; Torque; Acidosis; Muscle Contraction; Electromyography
PubMed: 37996974
DOI: 10.14814/phy2.15876 -
Sensors (Basel, Switzerland) 2011Muscle fatigue is an established area of research and various types of muscle fatigue have been investigated in order to fully understand the condition. This paper gives... (Review)
Review
Muscle fatigue is an established area of research and various types of muscle fatigue have been investigated in order to fully understand the condition. This paper gives an overview of the various non-invasive techniques available for use in automated fatigue detection, such as mechanomyography, electromyography, near-infrared spectroscopy and ultrasound for both isometric and non-isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who wish to select the most appropriate methodology for research on muscle fatigue detection or prediction, or for the development of devices that can be used in, e.g., sports scenarios to improve performance or prevent injury. To date, research on localised muscle fatigue focuses mainly on the clinical side. There is very little research carried out on the implementation of detecting/predicting fatigue using an autonomous system, although recent research on automating the process of localised muscle fatigue detection/prediction shows promising results.
Topics: Humans; Isometric Contraction; Muscle Contraction; Muscle Fatigue; Myography; Signal Processing, Computer-Assisted; Spectroscopy, Near-Infrared; Sports Medicine
PubMed: 22163810
DOI: 10.3390/s110403545 -
European Journal of Applied Physiology Apr 2023Hamstring strain injuries may occur due to differential fatigue and compromised mechanical properties among the hamstring muscles. We examined (1) the effect of fatigue...
PURPOSE
Hamstring strain injuries may occur due to differential fatigue and compromised mechanical properties among the hamstring muscles. We examined (1) the effect of fatigue on hamstrings active muscle stiffness, and (2) whether contraction type affects active muscle stiffness changes during a submaximal fatiguing task.
METHODS
Nine healthy males completed 99 submaximal knee flexions in isometric (ISO), concentric (CON), and eccentric (ECC) conditions. We measured the knee flexor maximal voluntary torque (MVT) (pre/post), shear wave velocity (SWV) during contraction and transverse relaxation times (T2) (pre/post) in biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM) muscles.
RESULTS
MVT decreased substantially after all conditions (- 18.4 to - 33.6%). The average relative torque sustained during the task was lower in CON than ISO and ECC, but absolute torque was similar. SWV interindividual responses were highly variable across muscles and contraction types. On average, BFlh SWV tended to increase in ISO (0.4 m/s, 4.5%, p = 0.064) but decreased in ECC condition (- 0.8 m/s, - 7.7%, p < 0.01). ST SWV decreased in CON (- 1.1 m/s, - 9.0%, p < 0.01), while it remained unchanged in ISO and ECC. SM SWV decreased in CON (- 0.8 m/s, - 8.1%, p < 0.01), but it was unaffected in ISO and variable in ECC.
CONCLUSION
Fatigue has a differential effect on the mechanical properties of the constituent hamstring muscles, as measured with shear wave elastography, depending upon contraction type. We found preliminary evidence that BFlh is more fatigued than ST or SM during eccentric contractions, which may explain its susceptibility to strain injuries.
Topics: Male; Humans; Hamstring Muscles; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Isometric Contraction; Torque; Electromyography
PubMed: 36494585
DOI: 10.1007/s00421-022-05104-0 -
Journal of Sports Science & Medicine Jun 2022The occurrence and mechanisms underlying non-local or crossover muscle fatigue is an ongoing issue. This study aimed to investigate crossover fatigue of the plantar...
The occurrence and mechanisms underlying non-local or crossover muscle fatigue is an ongoing issue. This study aimed to investigate crossover fatigue of the plantar flexor muscles. Sixteen recreationally active males (n = 6) and females (n = 10) visited the laboratory for four sessions and performed a single 5-s pre-test maximal voluntary isometric contraction (MVIC) with each plantar flexors muscle. Thereafter, the fatigue intervention involved two 100-s MVICs (60-s recovery) with their dominant plantar flexors or rested for 260-s (control). Subsequently, in two separate sessions, Hoffman reflexes (H-reflex) were evoked in the non-dominant, non-exercised, leg before and following the dominant leg fatigue or control intervention (Fatigue-Reflex and Control-Reflex conditions). MVIC forces and volitional (V)-waves were monitored in the non-dominant leg in the other two sessions (Fatigue-MVIC and Control-MVIC) before and after the intervention (fatigue or control) as well as during 12 repeated MVICs and immediately thereafter. Despite the force reduction in the dominant leg (42.4%, = 0.002), no crossover force deficit with single (F = 0.02, = 0.88, = 0.003) or repeated (F = 0.006, ) MVIC testing were observed. The H-reflex did not change after the fatigue (F = 0.51; = 0.49; 0.06) or repeated MVICs (F = 0.27; = 0.61; 0.03). There were also no crossover effects of fatigue on the V-wave with single (F = 3.71, ) or repeated MVICs (F = 1.45, ). Crossover fatigue was not evident with the plantar flexors nor any significant changes in H-reflex and V-waves in the soleus muscle. This finding suggests that crossover fatigue may not necessarily occur in slow-twitch predominant muscle groups.
Topics: Electromyography; Female; Humans; Isometric Contraction; Male; Muscle Fatigue; Muscle, Skeletal
PubMed: 35719232
DOI: 10.52082/jssm.2022.214 -
Scientific Reports Jun 2021Muscle fatigue is a complex phenomenon enclosing various mechanisms. Despite technological advances, these mechanisms are still not fully understood in vivo. Here,... (Observational Study)
Observational Study
Muscle fatigue is a complex phenomenon enclosing various mechanisms. Despite technological advances, these mechanisms are still not fully understood in vivo. Here, simultaneous measurements of pressure, volume, and ribcage inspiratory muscle activity were performed non-invasively during fatigue (inspiratory threshold valve set at 70% of maximal inspiratory pressure) and recovery to verify if inspiratory ribcage muscle fatigue (1) leads to slowing of contraction and relaxation properties of ribcage muscles and (2) alters median frequency and high-to-low frequency ratio (H/L). During the fatigue protocol, sternocleidomastoid showed the fastest decrease in median frequency and slowest decrease in H/L. Fatigue was also characterized by a reduction in the relative power of the high-frequency and increase of the low-frequency. During recovery, changes in mechanical power were due to changes in shortening velocity with long-lasting reduction in pressure generation, and slowing of relaxation [i.e., tau (τ), half-relaxation time (½RT), and maximum relaxation rate (MRR)] was observed with no significant changes in contractile properties. Recovery of median frequency was faster than H/L, and relaxation rates correlated with shortening velocity and mechanical power of inspiratory ribcage muscles; however, with different time courses. Time constant of the inspiratory ribcage muscles during fatigue and recovery is not uniform (i.e., different inspiratory muscles may have different underlying mechanisms of fatigue), and MRR, ½RT, and τ are not only useful predictors of inspiratory ribcage muscle recovery but may also share common underlying mechanisms with shortening velocity.
Topics: Adult; Electromyography; Female; Humans; Intercostal Muscles; Male; Muscle Contraction; Muscle Fatigue; Muscle Relaxation; Muscle Strength; Plethysmography; Young Adult
PubMed: 34127754
DOI: 10.1038/s41598-021-92060-y