RESEARCH: studies reviewed this week - 28 September 2020 to 04 October 2020

NUTRITION: Effect of Dark Chocolate Supplementation on Tissue Oxygenation, Metabolism, and Performance in Trained Cyclists at Altitude

This study set out to test a snart hypothesis: "dark chocolate (DC) is high in flavonoids and has been shown to increase nitric oxide in the blood. Increased nitric oxide has the potential to improve delivery of oxygen to muscle, especially in hypoxic conditions, such as altitude. Our aim was to assess the impact of DC supplementation on cycling performance at altitude". Unfortunately for all of us chocolate fans the authors found that:

DC had no effect on the TT performance or oxygenation status in either the prefrontal cortex or muscle. The authors conclude that, although it provided some metabolic benefit, DC is not effective as an ergogenic aid during TT cycling at simulated altitude.

PRACTICAL TAKE AWAY - dark chocolate does not benefit altitude performance.

NUTRITION: Athletes using ergogenic and medical sport supplements report more favourable attitudes to doping than non-users

I've always found it interesting to think about who is most likely to take drugs for sport performance. Based on what I've ready previously I always assumed that it was mostly an environment-driven model with pressure from sponsors and teams. Of course as always it's much more complicated than that and this study provided an additional factor that I would never have considered:

Use of ergogenic, medical and sport food/drink supplements was indirectly related to doping attitudes via sport supplement beliefs.

PRACTICAL TAKE AWAY - for this study I think it's best to quote directly from their conclusions: "Sport practitioners administering ergogenic and medical sport supplements to athletes may need to provide additional anti-doping education to counteract any favourable attitudes towards doping."

NUTRITION: Gluconeogenesis during endurance exercise in cyclists habituated to a long‐term low carbohydrate high‐fat diet

There are many theories about how diet affects the fuels used and generated during exercise. This study used "stable isotope tracers to study glucose production kinetics during a 2 h ride in cyclists habituated to either a LCHF or mixed macronutrient diet". This is an important study for multiple reasons: it used tracers and measured the actual glucose production kinetics and it used athletes habituated to a LCHF diet in the study. This removes many of the doubts typically associated with performance-only effects and athletes who have not fully habituated to a diet. The authors found that:

Rates of endogenous glucose production (EGP) and hepatic glycogenolysis (GLY) both at rest and during exercise were significantly lower in the LCHF group than the mixed diet group.

No difference was detected in rates of gluconeogenesis (GNG) between groups at rest or during exercise.

We conclude that athletes on a LCHF diet do not compensate for reduced glucose availability via higher rates of glucose synthesis compared to athletes on a mixed diet. Instead, GNG remains relatively stable, whereas glucose oxidation and GLY are influenced by dietary factors.

PRACTICAL TAKE AWAY - a LCHF diet does not improve gluconeogenesis during exercise so is not an intervention that should be used if this is the intended result.

NUTRITION: Role of submaximal exercise in promoting creatine and glycogen accumulation in human skeletal muscle

This study has useful implications for recovery after exercise as it investigated the "effect of glycogen-depleting exercise on subsequent muscle total creatine (TCr) accumulation and glycogen resynthesis during postexercise periods when the diet was supplemented with carbohydrate (CHO) or creatine (Cr) + CHO". After a thorough protocol that used muscle biopsies at 6h and 5 days after exercise, the authors found that:

A single bout of exercise enhanced muscle Cr accumulation.

Ingesting Cr with CHO also augmented glycogen supercompensation in the exercised muscle.

PRACTICAL TAKE AWAY - creatine ingestion may have additional benefits for athlete recovery including glycogen supercompensation after exercise. This may be particularly useful for endurance athletes during a strength training block.

HEAT: Benefits of heat re-acclimation in the lead-up to the Tokyo Olympics

This is a fantastic guide and protocol on how to effectively prepare for a hot race. The steps involved are:

  • Heat acclimation for 2 weeks;
  • Normal training or taper for 2-3 weeks with occassional active/passive heat exposure sessions;
  • Re-acclimation at the competition venue for 1 week prior to the event.

PRACTICAL TAKE AWAY - it is possible to prepare for a hot racing using a multi-step approach that still allows for optimal training leading up to the event.

STRENGTH: Concurrent Complex and Endurance Training for Recreational Marathon Runners

I have shared a few studies about strength training and running economy (plyometrics for ultra-marathoners, explosive strength training, meta analysis of strength training controlled trials, depth jumps). This study compared the effects of "complex strength training (CPX), heavy strength training (HST) and endurance-strength (EST) combined with running endurance training on neuromuscular adaptations and running performance". CPX is strength training that combines strength training with plyometrics in the same session.

The authors found that:

6-week of concurrent CPX or HST and endurance training resulted in similar improvement in maximum strength, RE, and vVO2max.

Both CPX and HST training resulted in greater improvements in eccentric strength and RE compared to EST that performed concurrent endurance- strength and endurance training.

PRACTICAL TAKE AWAY - keep doing your strength training whatever modality that may take.

No comments: