RESEARCH: studies I shared this week: 10-16 October 2022

All of the studies I've shared (~500 studies) are available on the RESOURCES PAGE.

ALTITUDE: Altitude Preexposure Recommendations for Inducing Acclimatization

I've shared plenty of studies on acclimation to altitude (search for "altitude" on the resources page), but I haven't seen that much on intermittent or discontinuous exposure. In practice, for non-elite athletes, this is probably the most likely form of altitude acclimation they can achieve.

STUDY DETAILS -

1. There is ample evidence that intermittent altitude exposures do induce ventilatory acclimatization and improve work performance.
2. We found that AMS was absent at 4300 m immediately following 15 days of 4-h daily exposure to 4300 m.
3. Moreover, most of these studies used hypobaric chambers, and the exposures were to very high altitudes (>4000 m) that cannot be easily attained in the natural environment by individuals residing at low altitude.
4. There is evidence that 5 or more days above 3000 m within the last 2 months prior to an ascent to high altitude will significantly decrease AMS.

PRACTICAL TAKEAWAY - the best practice for altitude acclimation is staying for 3-4 weeks at ~2000m. This isn't always possible, however, athletes can achieve certain aspects of acclimation (ventilatory acclimation) in shorter periods of time and reduce the possibility of AMS through shorter, more carefully considered acclimation periods.

TRAINING: Comparison of High- vs. Low-Responders Following a 6-Month XC Ski-Specific Training Period

STUDY DETAILS -

1. The present study used a multidisciplinary approach to compare high- and low-responders following a 6-month training period in endurance athletes transferring to cross-country (XC) skiing.
2. High-responders improved maximum oxygen uptake (VO2max) in treadmill running as well as peak oxygen uptake and power output at 4 mmol/L treadmill roller-ski skating which differed from a corresponding non-significant change in low-responders.
3. High-responders performed greater training loads and had lower incident of injury/illness.
4. Possibly, the higher motivation and stronger coach-athlete relationships in high-responders contributed to more individually optimized training and recovery routines, and thereby more positive performance-development.

PRACTICAL TAKEAWAY - maintaining motivation and building strong relationships with coaches to ensure individualized training and feedback may be key to increasing training load and therefore improving performance.

HYDRATION: Does Hypohydration Really Impair Endurance Performance?

STUDY DETAILS -

1. An important consideration that has received little attention, is the methods that have traditionally been used to investigate how hypohydration afects exercise outcomes, as those used may confound the results of many studies.
2. First, subjects involved in studies are generally not blinded to the intervention taking place (i.e. they know what their hydration status is), which may introduce expectancy efects.
3. Second, most of the methods used to induce hypohydration are both uncomfortable and unfamiliar to the subjects, meaning that alterations in performance may be caused by this discomfort, rather than hypohydration per se.
4. On balance, these recent blinded hydration studies suggest hypohydration equivalent to 2–3% body mass decreases endurance cycling performance in the heat, at least when no/little fluid is ingested

PRACTICAL TAKEAWAY - stay hydrated to maximize your performance.

SUPPLEMENT: Ergogenic Effect of Nitrate Supplementation

STUDY DETAILS -

1. A clear ergogenic effect of NO3 - supplementation in recreationally-active, young, healthy men across different exercise paradigms and NO3 - supplementation parameters; however, the effect size of NO3 - supplementation was objectively small.
2. NO3 - supplementation has more limited utility as an ergogenic aid in participants with excellent aerobic fitness that have optimized other training parameters.

PRACTICAL TAKEAWAY - the benefits of nitrate supplementation are not that great so it's a "must have", but there's probably no harm in using them so if they caught any issues for you then you may as well take them.

NUTRITION: Macronutrient consumption prior to, and during, a mountain marathon

STUDY DETAILS -

1. This field study examined athletes’ food intake prior to, and during a mountain marathon event to assess compliance with recommendations and to identify associations with performance.
2. Despite reported intentions to increase carbohydrate (CHO) consumption in the week prior to the event, there was no significant change in consumption across the week.
3. CHO and energy consumption prior to the event were positively associated with performance.
4. Energy and CHO consumption during the event were also positively correlated with performance, despite most participants again failing to meet recommendations for intake.

PRACTICAL TAKEAWAY - make sure to follow best practice recommendations for CHO intake prior and during your event.

NUTRITION: Highly Branched Cyclic Dextrin and its Ergogenic Effects in Athletes: A Brief Review

STUDY DETAILS -

1. Highly branched cyclic dextrin (HBCD) is a relatively new carbohydrate source that has gained much popularity in sports nutrition supplements, quickly becoming one of the most popular sports and fitness supplements globally.
2. The mean muscle glycogen contents were significantly higher after administration of the beverage with the lower osmolality, and the mean rate of glycogen synthesis was significantly higher, especially during the first hour.
3. HBCD is a carbohydrate known to have a low osmolality.
4. The increase in RPE at 30 and 60 minutes after ingestion was significantly lower after consuming HBCD than maltodextrin.
5. Swimming time to exhaustion was almost 70% longer after receiving HBCD compared to glucose or water.These results suggest that HBCD may help maintain blood glucose availability for a relatively long time during exhaustive endurance exercise.
6. Based on the results of the available studies, HBCD may provide increased performance or endurance compared to other carbohydrate sources, such as maltodextrin and glucose, especially in conditions of low carbohydrate feeding.

PRACTICAL TAKEAWAY - cyclic dextrin looks like a promising carbohydrate source for endurance and it's worth trying produces that include it.