RESEARCH: Studies reviewed this week: 28 December 2020 to 03 January 2021

HEAT & ALTITUDE: Heat Versus Altitude Training for Endurance Performance at Sea Level

Altitude has long been known as an environmental factor that can aid in performance. More recently, heat acclimation has also been debated and considered as a performance enhancing intervention for endurance athletes. This review set out to determine which environmental training stimulus is preferred for endurance athletes. The authors first compared altitude and heat training adaptations noting that:

  • Improvements in the sea-level performance of elite endurance athletes after altitude training primarily originate from hypoxia-induced erythropoiesis
  • The primary adaptation after heat training is a marked expansion of plasma volume. Whether this adaptation is responsible for improvements in temperate endurance performance remains a point of contention.
  • Taken together, it is clear that although some overlap exists in the physiological adaptations after heat versus altitude training, the prevailing mechanisms contributing to beneficial changes in sea-level endurance performance in temperate conditions are dissimilar.

Based on their research the authors concluded that:

The physiological adaptations acquired through conventional altitude training practices are superior for temperate sea-level endurance exercise performance of well-trained athletes compared to those gained with heat training.

PRACTICAL TAKE AWAY - altitude training may provide a greater performance enhancing effect compared to heat training for sea-level, temperate weather performances.

TRAINING: The Effects of Continuous Compared to Accumulated Exercise on Health

In this review the authors set out to "examine if exercise interventions consisting of a single bout of exercise compared with interventions comprising the same total duration, mode, and intensity of exercise accumulated over the course of the day have different effects on health outcomes in adults". While this review was looking at health, it could be interesting for athletes who are considering how to structure their training days.

The authors found that:

There were no differences between accumulated and continuous groups for any cardiorespiratory fitness or blood pressure outcomes. A difference was found in body mass changes from baseline to post-intervention in favour of accumulated exercise compared with continuous. No differences were observed for any other blood biomarker (total cholesterol, high-density lipoprotein cholesterol, triglycerides, fasting blood glucose, and fasting insulin).

The authors concluded that:

Collectively our findings suggest that adults are likely to accrue similar health benefits from exercising in a single bout or accumulating activity from shorter bouts throughout the day.

PRACTICAL TAKE AWAY - if you're struggling to fit in all your training into "singles" each day, there may be similar benefit for health for accumulating the same load over more sessions.

NUTRITION: Carbohydrate dose influences liver and muscle glycogen oxidation and performance during prolonged exercise

This is a useful paper to have in your research archives as it is the basis of the 90g/hr recommendation for CHO ingestion.

The authors tested multiple different blends (glucose and fructose) and quantities (60g, 75g, 90g, and 112g per hour). They concluded that:

There was no linear dose response for CHO ingestion, with 90 g/h1 of glucose-fructose being optimal in terms of TT performance and fuel selection.

PRACTICAL TAKE AWAY - there is more recent research suggesting that up to 120g/hr of CHO may be optimal, however, this important work is the basis for most nutrition companies current recommendations and nutrition formulations. It's important to try and achieve at least the recommended 90g/hr if you want to optimise endurance performance.

NUTRITION: Ice slurry ingestion before and during exercise inhibit the increase in core and deep-forehead temperatures in the second half of the exercise in a hot environment

This study set out to "investigate whether the ingestion of ice slurry before and during exercise can inhibit [the core temperature increase that occurs during exercise] acceleration". The authors tested the deep-forehead and rectal temperatures of athletes (a control group) and an intervention group who performed a 60' bout of exercise at 34C. The intervention group ingested 7.5g/kg within 30' of exercise and then 1.25g/kg every 10' during exercise.

The findings were that:

The rectal temperature and deep-forehead temperature during the second half of the exercise session were significantly reduced after ingestion of the ice slurry before and during exercise. In addition, the rate of increase in Tre and Tdeep head slowed during the second half of the exercise session after the ingestion of the ice slurry before and during exercise.

PRACTICAL TAKE AWAY - if you have the means to do so, in a hot race taking an ice slurry could reduce the rate of temperature increases and therefore may improve performance.

NUTRITION: Protein supplementation increases adaptations to endurance training

This review article looked into the research on protein supplementation and it's impact during chronic endurance training on a range of factors including aerobic capacity, body composition and exercise performance.

The authors found that compared to control, protein supplementation showed:

  • Greater improvements in aerobic capacity measured by mixed peak oxygen uptake and peak workload power.
  • Had a greater lean mass gain.
  • Had a greater improvement in time trial performance.

The protein supplementation used as the criteria was 22g of protein taken either before or after exercise.

PRACTICAL TAKE AWAY - there may be benefit to using protein supplementation during heavy training even for endurance performance goals.

TRAINING: Less Is More—Cyclists-Triathlete’s 30 min Cycling Time-Trial Performance Is Impaired With Multiple Feedback Compared to a Single Feedback

Athletes now have access to multiple different data sets and feedback when they are training and racing. This study compared multiple vs single feedback on time trial performance. The findings were:

  • Performance was impaired with multiple feedback compared to single feedback.
  • [athletes] glanced at power and time corresponding to [data] they use during training.
  • Overloading athletes with feedback may decrease performance.

PRACTICAL TAKE AWAY - choose the data available to us carefully and to use the same data in training and in races.

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