RESEARCH: Studies reviewed this week: 5 April 2021 to 11 April 2021

RECOVERY: Effect of the Depth of Cold Water Immersion on Sleep Architecture and Recovery Among Well-Trained Male Endurance Runners

Two previous studies that I shared (here and here) showed that cold-water immersion or ice-baths were not beneficial for performance. This study looked at whole-body cold-water immersion "after high-intensity, intermittent running exercise on sleep architecture and recovery kinetics among well-trained runners". I find this interesting because it's looking at the CWI as an indirect means of improving recovery rather than the benefit of the CWI itself.

The protocol involved whole-body immersion for 10' after a simulated trail run. The authors found that:

Slow-wave sleep (SWS) proportion was higher during the first 180 min of the night in WHOLE compared with PARTIAL.
Heart rate variability analysis showed a significant reduction in RMSSD, low frequency (LF), and high frequency (HF) in WHOLE compared with both PARTIAL and CONT during the first sequence of SWS.
No differences between conditions were observed for any markers of fatigue and muscle damage throughout the 48-h recovery period.

PRACTICAL TAKEAWAY - whole-body CWI may be beneficial because of the recovery benefits of better sleep after the CWI intervention.

SLEEP: The effect of acute sleep deprivation on skeletal muscle protein synthesis and the hormonal environment

Sleep is one of the topics I have shared a significant amount of research on recently (see Resources page). This study adds some more value to those previous studies because it investigates the impact a single night of sleep deprivation. The authors set out "to determine if acute sleep deprivation blunts skeletal muscle protein synthesis and promotes a catabolic environment". The authors found that:

Acute sleep deprivation reduced muscle protein synthesis by 18%.
leep deprivation increased plasma cortisol by 21% and decreased plasma testosterone by 24%.
No difference was found in the markers of protein degradation.

PRACTICAL TAKEAWAY - a single night of sleep deprivation is sufficient to "induce anabolic resistance and a procatabolic environment". Try not to miss even a single night of sleep.

SLEEP: Role of physical activity and fitness on sleep in sedentary middle-aged adults

This study set out "to investigate the association of objectively-measured sedentariness, physical activity levels, and physical fitness with sleep quantity and quality". The value here is to better understand the factors that influence sleep.

Reduced levels of sedentariness, greater VO2 max, and greater muscular strength were positively related to improved objective sleep quantity and quality.
Higher levels of overall physical activity, VO2max, and muscular strength were related to better subjective sleep quantity and quality.

PRACTICAL TAKEAWAY - reduced sedentariness and more physical activity improve sleep quality and quantity.

NUTRITION: Is There an Exercise-Intensity Threshold Capable of Avoiding the Leaky Gut?

This review looked at the available research on intestinal markers and gut permeability during exercise. The key notes from the authors are:

It was recently shown that 60 min of vigorous endurance training at 70% of the maximum work capacity led to the characteristic responses of leaky gut.
It is believed that other factors may contribute to this effect, such as altitude, environmental temperature, fluid restriction, age and trainability.
Moderate physical training and dietary interventions such as probiotics and prebiotics can improve intestinal health and gut microbiota composition.

PRACTICAL TAKEAWAY - a relatively low intensity will lead to leaky gut issues during exercise. Where possible train your gut and make sure to eat pro- and pre-biotics to improve the gut microbiome.

COVID-19: Post-acute COVID-19 syndrome

This comprehensive review provides a large amount of detail on the potential long-term effects after acute COVID-19 cases. The report is detailed and thorough and a useful reference in case you have any long or lingering issues after COVID-19.

This diagram outlines some of the potential post-acute COVID-19 symptoms:

PRACTICAL TAKEAWAY - if you have COVID-19 please be careful and consider any post-COVID symptoms and impacts before returning to sport.

NUTRITION: Carbohydrate restriction following strenuous glycogen-depleting exercise does not potentiate the acute molecular response associated with mitochondrial biogenesis in human skeletal muscle

CO restriction prior to exercise has shown some benefit and led to strategies such as the train-low race-high strategy. In this study the authors set out to "determine whether post-exercise CHO restriction following strenuous exercise combining continuous cycling exercise (CCE) and sprint interval exercise could affect the gene expression related to mitochondrial biogenesis and oxidative metabolism in human skeletal muscle".

The key findings were that:

Compared to pre-exercise, strenuous cycling led to a severe muscle glycogen depletion (> 90%) and induced a large increase in PGC1A and PDK4 mRNA levels (~ 20-fold and ~ 10-fold, respectively) during the acute recovery period in both trials.
CHO restriction during the 3-h post-exercise period blunted muscle glycogen resynthesis but did not increase the mRNA levels of genes associated with muscle adaptation to endurance exercise, as compared with abundant post-exercise CHO consumption.

PRACTICAL TAKEAWAY - CHO restriction after training is not beneficial. Eat after training!

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