RESEARCH: Studies reviewed this week: 23 November 2020 to 29 November 2020

PHYSIOLOGY: Diurnal versus Nocturnal Exercise—Impact on the Gastrointestinal Tract

Gastrointestinal issues are one of the biggest factors for the reasons for DNFs in ultramarathons. As ultramarathons often take place over 24-hour periods runners will be running both during the day and at night. This study set out to determine whether there are any differences between "diurnal versus nocturnal exercise on gastrointestinal integrity and functional responses, plasma LBP and sCD14 concentrations (as indirect indicators of endotoxin responses), systemic inflammatory cytokine profile, gastrointestinal symptoms and feeding tolerance"

The authors concluded that:

Nocturnal exercise instigates greater gastrointestinal functional perturbations and symptoms compared to diurnal exercise.

PRACTICAL TAKE AWAY - night-time gastrointestinal function is worse than during the day and this is something that may warrant consideration in creating an ultramarathon nutrition plan.

NUTRITION: Pectin-Alginate Does Not Further Enhance Exogenous Carbohydrate Oxidation in Running

I've shared a previous study that showed that hydrogels do not support the claimed benefits purported by the manufacturers. While most studies on these products have concentrated on cyclists, this study looked at runners testing the difference between normal maltodextrin and fructose drinks vs maltodextrin, fructose, pectin and alginate. There was no additional benefit for the drinks with pectin and alginate and the authors concluded:

To maximize exogenous carbohydrate oxidation during moderate-intensity running, athletes may benefit from consuming glucose(polymer)-fructose mixtures over glucose-based carbohydrates alone, but the addition of pectin and sodium alginate offers no further benefit.

PRACTICAL TAKE AWAY - if you're looking for a solution to gastrointestinal issues or products that allow you to eat more during an ultramarathon then drinks with pectin and alginate are no better than normal drinks.

TRAINING: Superior performance improvements in elite cyclists following short‐interval vs effort‐matched long‐interval training

I've shared some studies in the past about improving intervals using fast starts or using a high-intensity decreasing interval to maximise the time at VO2Max. This study compared effort-matched short intervals (3 x [13 x 30"/15"] / 3') and longer intervals (4 x 5' / 2.5'). The authors concluded:

The data thus demonstrate that the present SI protocol induces superior training adaptations compared with the present LI protocol in elite cyclists.

When I shared this study on twitter I received multiple responses and thoughts from other coaches and athletes. There is some disagreement that this is the best protocol for improving VO2Max and also some concerns about the control group of the study. I recommend that you read the replies that tweet and also consider listening to episodes 21, 22 and 23 of the Empirical Cycling podcast where they discuss VO2 Max development in more detail.

PRACTICAL TAKE AWAY - there are multiple different ways to structure intervals and there may be benefit to shorter, HIIT type intervals for improving VO2 Max (however, I would encourage you to read and listen to the additional links to make up your own mind).

ALTITUDE / HEAT: Special Environments: Altitude and Heat

This consensus paper in the Human Kinetics Journal looks at heat and altitude strategies to prepare for competition. It is a detailed and useful guide that I recommend reading. In the conclusion the authors note:

The use of altitude and heat as interventions to prepare for competitions in these conditions is essential and supported by a large body of evidence. Altitude training in particular further provides performance benefits for competition in normal environmental conditions (i.e., sea level), with heat training possibly aiding performance in the cool environment. It seems sensible for coaches and elite athletes, especially on the endurance side of athletics, to investigate the use of altitude and heat training.

PRACTICAL TAKE AWAY - it is important to consider heat and altitude preparation if you want to optimise your performance.

PSYCHOLOGY: Talking yourself out of exhaustion: the effects of self-talk on endurance performance

I recently attended a presentation by Samuele Marcora (my notes here) where he provided an overview of his psychobiological model of fatigue. I was intrigued and started digging more into his studies. This study "investigated the effects of a frequently used psychological strategy, motivational self-talk (ST), on RPE and endurance performance".

The authors found that:

Motivational self-talk significantly enhanced time to exhaustion test from pre-test to post-test with no change in the control group.

Motivational self-talk significantly reduced RPE at 50% isotime with no significant difference in the control group.

PRACTICAL TAKE AWAY - motivational self-talk is a useful technique to improve endurance performance.

TRAINING: Effects of training-induced fatigue on pacing patterns in 40-km cycling time trials

This study set out to investigate whether or not "fatigued athletes choose the same pacing pattern (PP) as when they have recovered". I think this is a useful study for athletes who compete in multiple-day competitions, but also for designing training as there could be an impact on how well athletes learning pacing when they are fatigued. The design of the study used three time trials (TT):

TT were conducted before (TT1) and after (TT2) a 6-d training period. A third TT was carried out after 72 h of recovery (TT3).

Training days consisted of two cycling sessions: mornings, 1 h at 95% of lactate threshold or 3 × 5 × 30 s all-out sprint; afternoons, 3 h at 80% individual anaerobic threshold. Four-kilometer split times (min) and RPE were recorded during TT.

The results showed that:

Performance decreased from TT1 to TT2 and increased from TT2 to TT3. PP showed a significant difference between TT1 and TT2 as well as between TT2 and TT3. In TT1 and TT3, cyclists started faster in the first 4 km compared with TT2. RPE course showed no significant difference between TT.

PRACTICAL TAKE AWAY - when fatigued, athletes automatically adjusted their pacing. Practice your race pacing in a rested state if you're trying to simulate race conditions closely.

No comments: