RESEARCH: Studies reviewed this week: 22 February 2021 to 28 February 2021

ALTITUDE: Parasympathetic withdrawal increases heart rate after 2 weeks at 3454 m altitude

This paper set out to determine the mechanisms for elevated heart rate due to chronic hypocic conditions. The authors "investigated the relative contributions of the sympathetic and parasympathetic nervous systems, along with potential non‐autonomic mechanisms, by individual and combined pharmacological inhibition of muscarinic and/or β‐adrenergic receptors".

The authors found that:

Our results identify a reduction in cardiac parasympathetic activity as the primary mechanism underlying the elevated HR associated with 2 weeks of exposure to hypoxia.
These effects of chronic hypoxia on autonomic control of the heart may concern not only high altitude dwellers, but also patients with disorders that are associated with hypoxaemia.

PRACTICAL TAKEAWAY - it appears that a suppression of parasympathetic activity may be the cause of elevated heart rate at high altitude. Perhaps using parasympathetic activities (such as HRV biofeedback) may increase the rate of adaption to altitude?

NUTRITION: The effect of daily protein supplementation, with or without resistance training for 1 year, on muscle size, strength, and function in healthy older adults

I believe in the importance of strength training and also the need for enough protein for athletes. This study is interesting because it looks to see if protein alone is enough to maintain muscle mass and if not, how much strength training is required.

The authors found that:

  • Collagen protein and whey protein supplementation did not affect any measured parameter compared to carbohydrates.
  • Heavy resistance training 3 times weekly with whey protein supplementation improved the quadriceps cross-sectional area (qCSA) and isometric knee extensor strength.
  • Light-intensity resistance training 3-5 times/wk with whey protein supplementation did not improve the qCSA size, but increased dynamic knee extensor strength.

PRACTICAL TAKEAWAY - protein alone is not enough to maintain strength or improve muscle mass. Strength training is also required.

NUTRITION: Protein Ingestion before Sleep Increases Muscle Mass and Strength Gains during Prolonged Resistance-Type Exercise Training in Healthy Young Men

I've shared a couple of papers before on pre-sleep protein: pre-sleep casein protein does not affect next day appetite, pre-sleep protein and muscle related outcomes. This study looks at pre-sleep protein impacts "on muscle mass and strength gains during resistance-type exercise training". The authors found:

Muscle strength increased after resistance exercise training to a significantly greater extent in the protein-supplemented (PRO) group than in the placebo-supplemented (PLA) group.
Both type I and type II muscle fiber size increased after exercise training, with a greater increase in type II muscle fiber size in the PRO group than in the PLA group.

PRACTICAL TAKEAWAY - take your pre-sleep protein!

TRAINING: Cardiorespiratory Responses to Constant and Varied-Load Interval Training Sessions

This study looks into the best way to run intervals. The authors compare two sets of intervals with the same total load, but with a control using 4x4' intervals of the same intensity and the intervention group using 4x4' starting at a higher intensity and decreasing the intensity during the set.

The findings were that:

Average oxygen uptake during the high-intensity intervals was higher in the decremental session in cycling but not in running, as was the time spent >90% of VO2max and the time spent >90% of peak heart rate.
Average heart rate, pulmonary ventilation, and blood lactate concentration were higher during the decremental sessions in both cycling and running.

PRACTICAL TAKEAWAY - it appears that decreasing intensity over a set of intervals may be a more efficient way to perform the training.

ALTITUDE: Application of Altitude/Hypoxic Training by Elite Athletes

This fantastic paper from 2007 identified various altitude training modalities and also looked into the legality of using simulated altitude.

A few notes I took away from this article were:

The research findings regarding LH + TL via oxygen filtration are equivocal regarding erythropoietic effect, with two studies reporting significant increases in erythrocyte volume and/or total hemoglobin mass, whereas others found no significant erythropoietic response after LH + TL via oxygen filtration.
Recently, several of these altitude/hypoxic training strategies and devices underwent critical review by WADA for the purpose of potentially banning them as an illegal performance-enhancing substance/method. Ultimately, WADA decided to refrain from including artificially induced hypoxic conditions on the 2007 prohibited list.

PRACTICAL TAKEAWAY - there are multiple options for altitude training. Simulated altitude seems to be effective although in 2007 it was still considered relatively risky.

TRAINING: The Impact of a Single Stretching Session on Running Performance and Running Economy

This scoping review set out "to investigate the effects of a single bout of stretching on RE and running performance in athletes (e.g., recreational and elites) and non-athletes". The authors found that:

Although it was observed that a single static stretching exercise with a duration of up to 90 s per muscle group can lead to small improvements in RE, negative effects were reported in running performance.
It was also observed that a single bout of dynamic stretching only resulted in a negligible change in RE but a large increase in running performance.

PRACTICAL TAKEAWAY - use a dynamic stretching routine for a warm-up before training and if you are going to do static stretching later in the day, keep that to less than 60" per stretch.

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