Potential role of passively increased muscle temperature on contractile function

Rodrigues, Patrick; Trajano, Gabriel S.; Stewart, Ian B.; Minett, Geoffrey M.

doi:10.1007/s00421-022-04991-7

Cited by 14 publications

(14 citation statements)

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“…This possibility could potentially explain the covariation between peak‐to‐peak amplitudes and force parameters, which allowed the detection of a lower contractile activity at retest. This response could be due to alterations in calcium handling and/or muscle fluids 24,25 …”

Section: Discussionmentioning

confidence: 99%

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Ischemic preconditioning increases spinal excitability and voluntary activation during maximal plantar flexion contractions in men

Cruz,

Tramontin,

Oliveira

et al. 2024

Scandinavian Med Sci Sports

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The enigmatic benefits of acute limb ischemic preconditioning (IP) in enhancing muscle force and exercise performance have intrigued researchers. This study sought to unravel the underlying mechanisms, focusing on increased neural drive and the role of spinal excitability while excluding peripheral factors. Soleus Hoffmann (H)‐reflex /M‐wave recruitment curves and unpotentiated supramaximal responses were recorded before and after IP or a low‐pressure control intervention. Subsequently, the twitch interpolation technique was applied during maximal voluntary contractions to assess conventional parameters of neural output. Following IP, there was an increase in both maximum normalized force and voluntary activation (VA) for the plantar flexor group, with negligible peripheral alterations. Greater benefits were observed in participants with lower VA levels. Despite greater H‐reflex gains, soleus volitional (V)‐wave and sEMG amplitudes remained unchanged. In conclusion, IP improves muscle force via enhanced neural drive to the muscles. This effect appears associated, at least in part, to reduced presynaptic inhibition and/or increased motoneuron excitability. Furthermore, the magnitude of the benefit is inversely proportional to the skeletal muscle's functional reserve, making it particularly noticeable in under‐recruited muscles. These findings have implications for the strategic application of the IP procedure across diverse populations.

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Section: Discussionmentioning

confidence: 99%

“…This response could be due to alterations in calcium handling and/or muscle fluids. 24,25 Among all the effects described above, only the enlargement of the Mmax first amplitude was "counteracted" by IP. In monopolar M-waves, the first phase predominantly reflects propagating elements.…”

Section: δ Ip [See Interval]mentioning

confidence: 97%

Ischemic preconditioning increases spinal excitability and voluntary activation during maximal plantar flexion contractions in men

Cruz,

Tramontin,

Oliveira

et al. 2024

Scandinavian Med Sci Sports

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“…Acute passive heating can increase localized muscle blood flow up to 60.9% immediately after heat exposure (T mu ~ 37.4 °C) and induce metabolic vasodilation 2 . Increased muscle blood flow increases intramuscular pressure creating a spring‐like condition 9,36 (see Rodrigues et al 37 for review). Hence, fluid‐dependent increases in stiffness may optimize muscle force‐length properties during contraction 12,36 .…”

Section: Discussionmentioning

confidence: 99%

Increases in muscle temperature by hot water improve muscle contractile function and reduce motor unit discharge rates

Rodrigues

Orssatto

Trajano

et al. 2023

Scandinavian Med Sci Sports

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Purpose: Examine the effects of 42°C hot-water immersion on muscle contraction function and motor unit discharge rates. Voluntary and evoked contraction assessments were examined first with a concomitant increase in the core and muscle temperature, and thereafter with increased muscle temperature but cooled core temperature.Methods: Fifteen participants (24.9 ± 5.6 years) performed neuromuscular assessments before, after, and ~15min after either 90-min of 42°C (hot) or 36°C (control) water immersion. Maximal voluntary contraction (MVC) assessment of knee extension was performed along with surface electromyography (sEMG) (vastus lateralis and medialis [VL, VM]) and voluntary activation level (VAL). Resting evoked twitch was elicited for peak torque and time to peak torque analysis. In addition, the VL and VM motor unit discharge rates (MUDR) were measured.Results: After hot-water immersion (core temperature ↑1°C; muscle temperature ↑2.4°C), MVC torque and VAL decreased (p < 0.05). The sEMG (VL and VM) and peak twitch torque did not change (p > 0.05), while time to peak torque decreased (p = 0.007). The VL and VM MUDR decreased, showing a time effect, after both water immersion conditions (36 and 42°C) (p > 0.001). Fifteen minutes after the hot-water immersion (core temperature at baseline; muscle temperature ↑1.4°C), MVC torque returned to baseline, but VAL remained lower. The sEMG (VL and VM) remained unchanged. Peak twitch torque increased (p < 0.002) and time to peak torque remained lower (p = 0.028). The MUDR remained lower after both water immersion conditions (p < 0.05). Conclusion:Increased core temperature evoked by 42°C hot-water immersion decreases MVC torque and VAL. However, a passive increase in muscle temperature improved evoked muscle contractile function (i.e., time to peak torque [after] and peak twitch torque [~15 min after]). Moreover, a passive increase in muscle temperature reduced the required MUDR to attain the same torque.

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“…However, the fact that the heating treatment in the study by Kim et al (2020b) led to increased muscle strength despite no significant change in muscle mass suggests that adaptations other than hypertrophy could also contribute to enhanced force development following chronic heat exposure. Increased muscle contractility following a single heat exposure has been attributed to increased calcium kinetics and increased intramuscular fluid ( Rodrigues et al, 2022 ), but whether these physiological events played a role in the increased muscle strength in Kim’s study remains unknown.…”

Section: Introductionmentioning

confidence: 97%

Hot water immersion as a potential substitute for strength training during the COVID-19 pandemic

Kjertakov

Chandrasiri²,

Petersen³

2023

Front. Physiol.

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Potential role of passively increased muscle temperature on contractile function

Cited by 14 publications

References 87 publications

Ischemic preconditioning increases spinal excitability and voluntary activation during maximal plantar flexion contractions in men

Ischemic preconditioning increases spinal excitability and voluntary activation during maximal plantar flexion contractions in men

Increases in muscle temperature by hot water improve muscle contractile function and reduce motor unit discharge rates

Hot water immersion as a potential substitute for strength training during the COVID-19 pandemic

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