RESEARCH: Studies reviewed this week: 9 August 2021 to 15 August 2021

NUTRITION: Acute Ketogenic Diet and Ketone Ester Supplementation Impairs Race Walk Performance

Eating a LCHF diet or ketogenic diet has been shown to improve muscle fat utilisation, but to impair exercise performance. This study "aimed to determine if LCHF and ketone ester (KE) supplementation can synergistically alter exercise metabolism and improve performance". The participants who were elite race walkers "undertook a four-stage exercise economy test and real-life 10,000-m race before and after a 5-d isoenergetic high-CHO or LCHF diet. The LCHF group performed additional economy tests before and after diet after supplementation with 573 mg·kg−1 body mass KE, which was also consumed for race 2".

The results showed that:

The oxygen cost of exercise (relative V˙O2, mL·min−1·kg−1) increased across all four stages after LCHF. This occurred in association with increased fat oxidation rates, with a reciprocal decrease in CHO oxidation. Substrate utilization in the HCHO group remained unaltered.
The consumption of KE before the LCHF diet increased circulating KB, peaking at 3.2 ± 0.6 mM, but did not alter V˙O2 or RER.
Critically, race performance was impaired by ~6% relative to baseline in the LCHF group but was unaltered in HCHO.

PRACTICAL TAKEAWAY - despite also taking a ketone ester, the LCHF diet still resulted in impaired performance.

PHYSIOLOGY: Left Ventricular Dimensions and Diastolic Function Are Different in Throwers, Endurance Athletes, and Sprinters From the World Masters Athletics Championships

I didn't realize that "there is controversy whether a lifetime of heavy resistance training, providing pressure-overload, is harmful for left ventricular function" as most of the studies I review are focused on endurance athletes. This study looked into this topic while making comparison to endurance and sprint athletes. The authors found that:

Compared to age-matched historical controls, left ventricular diastolic function was not different in throwers, but superior in endurance athletes and sprinters.
Masters throwers have altered left ventricular dimensions and function vs. other athletes, but a lifetime of heavy resistance training does not appear to alter left ventricular function compared to age-matched controls.

PRACTICAL TAKEAWAY - we don't need to worry about heavy resistance training impacting heart function.

INJURY: A Cross-Sectional Study of Retired Great British Olympians (Berlin 1936–Sochi 2014): Olympic Career Injuries, Joint Health in Later Life, and Reasons for Retirement from Olympic Sport

It can be hard to tell whether or not high-level sports can have negative impacts on the body. Obviously sportspeople are seen as been very fit and healthy, but there's always an underlying concern about long-term injury and other issues. This study set out to investigate the career injury and long-term health of Olympic athletes. The authors found:

Lifetime Olympic career injury prevalence of 56.6%. Injury prevalence was highest in field athletics (81.0%), gymnastics (75.0%), and track athletics (67.7%).
Injuries most frequently occurred at the knee (19.0%), lower back (15.4%), and shoulder (11.5%).
Prevention strategies to reduce morbidity and improve long-term health should aim to reduce injuries specifically at the hip, knee, and lumbar spine.

PRACTICAL TAKEAWAY - althought this study didn't compare the Olympians to normal athletes, it is still interesting to see the high prevalence of injuries.

ALTITUDE: Cardiorespiratory Response and Power Output During Submaximal Exercise in Normobaric Versus Hypobaric Hypoxia

In this study the authors "examined cardiorespiratory responses and exercise performances during low- to high-intensity exercise at a fixed heart rate (HR) in both normobaric hypoxia (NH) and hypobaric hypoxia (HH) using a specific chamber where atmospheric oxygen concentration and barometric pressure as well as the abovementioned environmental factors [such as temperature, humidity, and fraction of inspired carbon dioxide] were precisely controlled".

They found that:

SpO2, PETCO2, and power output at fixed HRs (i.e., pedaling efficiency) in NH and HH were all significantly lower than those in NN.
Moreover, high-intensity exercise in HH induced greater decreases in SpO2 and power output than did high-intensity exercise in NH.
These results suggest that physiological responses and power output at a fixed HR during hypoxic exposure might depend on the method used to generate the hypoxic condition.

PRACTICAL TAKEAWAY - there definitely appears to be an impact of the way in which hypoxia is produced on the response. I recommend reading more about his in this article from Millet and Debevec.

DIET: Gluten-free diet can ameliorate the symptoms of non-celiac autoimmune diseases

This review looked into the research on gluten-free diets (GFD) and the associated impact on autoimmune diseases. The authors found that:

Reduction in symptoms of ADs after observance of a GFD was observed in 911 out of 1408 patients (64.7%) and in 66 out of the 83 selected studies (79.5%).
A GFD can suppress several harmful intraluminal intestinal events.
A GFD might represent a novel nutritional therapeutic strategy for classical non–gluten-dependent autoimmune conditions.

PRACTICAL TAKEAWAY - a GFD may be beneficial for non-celiacs to reduce autoimmune disease symptoms.

RACING: Pacing profiles and tactical behaviors of elite runners

What is the best way to pace a race? This review suggests different strategies dependent on distance and whether the race is a paced meet or a championship event. Some highlights I took included:

An "all-out" strategy, characterized by initial rapid acceleration and reduction in speed in the later stages, is observed during 100 m and 200 m events; 400 m runners also display positive pacing patterns, which is characterized by a reduction in speed throughout the race. Similarly, 800 m runners typically adopt a positive pacing strategy during paced "meet" races.
A U-shaped pacing strategy (characterized by a faster start and end than during the middle part of the race) is evident during world record performances at meet races in 1500 m, mile, 5000 m, and 10,000 m events.
In contrast, recent world record marathon performances have been characterized by even pacing, which emphasizes the differences between championship and meet races at distances longer than 800 m.

PRACTICAL TAKEAWAY - carefully consider your pacing strategy for your race and make sure to practice it in training.

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