RESEARCH: studies reviewed this month - February 2020

NUTRITION: Low-Carbohydrate Training Increases Protein Requirements of Endurance Athletes

Including some low-CHO training sessions has been shown to enhance aerobic adaptation and this has become popular to periodize throughout a training program. The authors set out to investigate if this approach requires other compensatory diet interventions to ensure the effectiveness of the training. In particular they started with the hypothesis that "exercise-induced amino acid oxidation is increased with low muscle glycogen, which may limit substrate availability for post-exercise protein synthesis".

The authors found that:

Phenylalanine oxidation (reciprocal of protein synthesis) was higher in LOW compared with HIGH, suggesting a greater amino acid requirement to support rates of whole-body protein synthesis.
Our findings suggest that performing endurance exercise with low-CHO availability increases protein requirements of endurance athletes.

PRACTICAL TAKE AWAY - when performing low-CHO training sessions include more protein in your diet. Some options include having a protein-centered breakfast before the low-CHO session, and / or eating a protein bar or drinking a protein drink during the exercise.

TRAINING: Efficacy of depth jumps to elicit a post-activation performance enhancement in junior endurance runners

Improving running speed and efficiency through incorporating plyometrics into training is a well-known intervention. This study set out "to determine the effect of performing depth jumps (DJ) pre-exercise on running economy (RE) and time to exhaustion (TTE) at the speed associated with maximal oxygen uptake (sO2max) in a group of high-performing junior middle-distance runners".

The findings showed that:

DJ produced moderate improvements in RE, which within the context of minimal detectable change is considered possibly beneficial. Differences in TTE and other physiological variables were most likely trivial.
The inclusion of a set of six DJ in the warm-up routine of a well-trained young male middle-distance runner is likely to provide a moderate improvement in RE.

PRACTICAL TAKE AWAY - including depth jumps may improve running economy. However, I would caution that plyometrics can be risky because of high load and therefore may cause injuries. Be careful including depth jumps in your plan before you're ready.

TRAINING: Monitoring the athlete training response: subjective self-reported measures trump commonly used objective measures

Measuring training load is important to ensure that athletes are progressing at an optimal rate while ensuring that they don't overtrain. There are multiple metrics and means of measuring training load ranging from defined objective metrics to subjective metrics such as RPE and mood. This study set out to compare objective and subjective metrics and to evaluate their response to training load.

"Objective measures, including those taken at rest (eg, blood markers, heart rate) and during exercise (eg, oxygen consumption, heart rate response), were compared against subjective measures (eg, mood, perceived stress). All measures were also evaluated for their response to acute and chronic training load."

Subjective and objective measures of athlete well-being generally did not correlate. Subjective measures reflected acute and chronic training loads with superior sensitivity and consistency than objective measures.
This review provides further support for practitioners to use subjective measures to monitor changes in athlete well-being in response to training. Subjective measures may stand alone, or be incorporated into a mixed methods approach to athlete monitoring, as is current practice in many sport settings.

PRACTICAL TAKE AWAY - use subjective measures (whether or not you choose to also use objective measures) to determine your response and adaptation to training load.

NUTRITION: Supplements and Nutritional Interventions to Augment High-Intensity Interval Training Physiological and Performance Adaptations

Nutrition considerations are critical to enhance adaptation and response to training. This narrative review investigates the potential interventions that may enhance HIIT. I recommend reading the full review to understand and investigate each supplement.

From the paper's conclusion:

Overall, the results show that sodium bicarbonate and beta-alanine show promise for enhancing HIIT adaptations and performance. Beetroot juice/nitrates appear to show some benefits; however, the majority of research suggests limited effectiveness at altering training adaptations, but future research is required to be more conclusive. Caffeine and creatine have the potential to augment HIIT, however, longer-term training studies are lacking. There is a lack of evidence to suggest that a high protein/EAA diet is required to enhance HIIT.
With regards to carbohydrate availability, training in a low glycogen state may alter metabolic stress and signaling pathways; however, there does not seem to be a clear performance advantage, and a periodized approach to carbohydrate intake seems warranted.

PRACTICAL TAKE AWAY - there are some nutrition interventions that could enhance HIIT training. If HIIT forms an important part of your training plan then it would be wise to understand these well and test them thoroughly to see if they help you.

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