RESEARCH: Studies reviewed this week: 11 May 2021 to 16 May 2021

PROTEIN: The Effect of Protein Supplementation versus Carbohydrate Supplementation on Muscle Damage Markers and Soreness Following a 15-km Road Race

Recovery after training and racing is important. Typical nutrition guidelines recommend taking in a certain amount of protein within a window period after the training session. In this study the authors set out to assess whether a protein supplement "could attenuate running-induced muscle soreness and other muscle damage markers compared to iso-caloric placebo supplementation".

The participants in the study followed the protocol below:

Participants received milk protein or carbohydrate supplementation, for three consecutive days post-race. Habitual protein intake was assessed using 24 h recalls. Race characteristics were determined and muscle soreness was assessed with the Brief Pain Inventory at baseline and 1-3 days post-race.

The results showed that:

Post-exercise protein supplementation is not more preferable than carbohydrate supplementation to reduce muscle soreness or other damage markers in recreational athletes with mostly a sufficient baseline protein intake running a 15-km road race.

PRACTICAL TAKEAWAY - protein supplementation is not significantly more important than carbohydrate consumption for recovery post race or post exercise provided you have enough protein in your diet.

NUTRITION: Long-term dietary patterns are associated with pro-inflammatory and anti-inflammatory features of the gut microbiome

This study investigated the gut microbiome with the goal of determining "whether we can nourish an anti-inflammatory gut ecosystem". In a massive study investigating 173 dietary factors and over 1000 participants, the authors set out to "unravel interactions between diet, gut microbiota and their functional ability to induce intestinal inflammation".

The full paper is available online so I would recommend reading it fully. Some of the key points from the paper include:

Higher intake of animal foods, processed foods, alcohol and sugar, corresponds to a microbial environment that is characteristic of inflammation, and is associated with higher levels of intestinal inflammatory markers.
Plant-based foods are linked to short-chain fatty acid (SCFA)-producers, microbial metabolism of polysaccharides and a lower abundance of pathobionts.

PRACTICAL TAKEAWAY - in general it appears that a plant-based diet increases the abundance of "good" gut microbiota.

RACING: Continuous Analysis of Marathon Running Using Inertial Sensors: Hitting Two Walls?

This study looks into the biomechanics of running and tries to assess the changes in athlete biomechanical metrics during the marathon. The authors set out "to assess the evolution of stride-by-stride spatio-temporal parameters, stiffness, and foot strike angle during a marathon and determine possible abrupt changes in running patterns".

The authors found that:

We observed gradual increases in contact time and duty factor as well as decreases in flight time, swing time, stride length, speed, maximal vertical force and stiffness during the race.
Two abrupt changes were also detected around km 25 and km 35. These two breaks are possibly due to the alteration of the stretch-shortening cycle combined with physiological limits.

PRACTICAL TAKEAWAY - there are distinct biomechanical phases during the marathon that we might be able to clearly identify and work on directly to improve performance in the future.

ALTITUDE: Variability in hemoglobin mass response to altitude training camps

Altitude training is something that I believe can make a big difference for athletes so I've shared multiple studies about it (see resources page). My own experience with training and racing at altitude has varied and I've often wondered whether I'm a responder or non-responder to altitude. This study set out to determine exactly that: "whether athletes can be classified as responders or non-responders based on their individual change in total hemoglobin mass (tHb-mass) following altitude training while also identifying the potential factors that may affect responsiveness to altitude exposure".

The results of the study show a range of responses:

From the fifteen athletes who participated in altitude training camps at least twice, 27% always had positive tHb-mass responses, 13% only negative responses, and 60% both positive and negative responses.

This lead the authors to the conclusion that:

In endurance athletes, tHb-mass is likely to increase after altitude training given that hypoxic stimulus is appropriate. However, great inter- and intra-individual variability in tHb-mass re-sponse does not support classification of an athlete permanently as a responder or non-responder

PRACTICAL TAKEAWAY - responses to altitude training vary both between individuals and over different exposures by the individuals. Carefully plan altitude training and accept that it may not always result in positive outcomes.

TRAINING: Association between dietary practice, body composition, training volume and sport performance in 100-Km elite ultramarathon runners

I've shared a couple of papers on the physiology of trail and ultramarathon runners which show that the characteristics of top performers in these races are similar to other running disciplines (see the PHYSIOLOGY section on the resources page). This study looked "to assess the potential associations between anthropometric, body composition, dietary and training factors and athletic performance in 100-Km elite ultramarathon runners".

There were correlations between multiple variables and performance, however:

After correcting for confounders, partial correlation analysis confirmed only the association between training volume and 100-Km race competition record.

PRACTICAL TAKEAWAY - higher training volumes were associated with greater performance in elite ultramarathon runners - train more

PHYSIOLOGY: Physiological Changes, Activity, and Stress During a 100-km–24-h Walking-March

Most ultramarathons are completed at low intensity, however, the physical demands of these events are still felt strongly by participants when compared to shorter, more intense efforts. This study set out "to evaluate changes in body composition and metabolism in long-endurance but low-intensity events". The test protocol followed athletes in a 100km race:

It was expected to complete the 100-km distance within 24 h, resulting in a calculated mean speed of 4.17 km/h, which fits to the mean speed observed.

The results showed that this event was particularly demanding despite the low speed:

We found significant elevations for muscle and cardiac stress markers as well as decreasing markers of lipid metabolism.
Although the intensity level demanded from our participants was low compared with other studies on (ultra-) marathons, the alteration of tested parameters was similar to those of high-intensity exercise.
Remarkably, the duration seems to have a greater influence on stress markers and metabolism than intensity.

PRACTICAL TAKEAWAY - long, low-intensity events and training are very demanding and should be carefully managed and considered within training plans.

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