RESEARCH: Studies from 10 to 16 June 24
Sharing research and insights from coaches, scientists and athletes to help us improve endurance performance.
This week’s quick summary:
Manipulating sleep duration perception changes cognitive performance
Which phases of the stroke cycle are propulsive in front crawl swimming?
Is foam rolling as effective as its popularity suggests?
A comparison of dietary protein digestibility in vegetarian athletes
Resistance-only and concurrent exercise induce similar myofibrillar protein synthesis
SLEEP: Manipulating sleep duration perception changes cognitive performance
The studies I have shared on sleep have shown the benefits of naps and sleep extension, while explaining the negative impacts of sleep restriction (see SLEEP). In this study, the authors set out “to test the effect of perceived sleep duration on cognitive performance focusing on how belief about sleep duration affects reaction time and brain activity”.
STUDY DETAILS
Sixteen healthy individuals (8 female, mean age 24.2±3.0 years) participated in the study.
Participants experienced an 8-hour sleep opportunity followed by a 5-hour sleep opportunity on consecutive nights.
Upon waking, participants were told they had either an 8-hour or 5-hour sleep, based on a manipulated clock.
Cognitive performance was assessed using 10-minute auditory psychomotor vigilance tests and subjective sleepiness ratings.
Results showed quicker reaction times when participants believed they had 8 hours of sleep after a 5-hour opportunity, and slower times when they thought they had 5 hours of sleep after an 8-hour opportunity. EEG data indicated significant changes in brain activity based on perceived sleep duration.
PRACTICAL TAKEAWAY
This study suggests that an individual’s perception of their sleep duration can impact their performance regardless of how much time they actually slept. This has implications for athletes using sleep trackers that may be inaccurate and lead to poor perceptions of their sleep. My recommendation for athletes is to follow a consistent sleep routine to ensure they achieve a long enough sleep duration and to assess their sleep quality based on how they feel rather than using a sleep tracker score.
PHYSIOLOGY: Which phases of the stroke cycle are propulsive in front crawl swimming?
A previous study I shared showed that swimmers adapt for any asymmetries in their stroke. While there is some adaptability and variation in an individual’s stroke, there are different phases of propulsion within the stroke. In this study, the authors set out “to identify which phases of the stroke cycle contribute to propulsion in front crawl swimming”.
STUDY DETAILS
The study involved 10 competitive swimmers, including both males and females.
Each swimmer performed front crawl swimming at their maximum speed for a duration of 25m in a swimming pool.
The researchers used underwater video analysis and motion capture technology to measure the swimmers' movements and the forces generated during different phases of the stroke cycle.
Results showed that the underwater pull and push phases were the most propulsive, generating the highest forward thrust.
The entry and recovery phases were found to contribute minimally to propulsion, primarily serving to position the arms for the next stroke cycle.
PRACTICAL TAKEAWAY
These results are not very surprising as it seems logical that the most propulsive phase of the stroke is after the catch during the push phase. However, there are some useful recommendations in the study such as “shortening the duration of the entry phase by a quarter may in theory avoid the overlap between entry and recovery and potentially improve performance”. My recommendation for swimmers is to incorporate drills that focus on performing a quick recovery phase of the stroke that leads into a faster entry phase to start the catch earlier.
RECOVERY: Is foam rolling as effective as its popularity suggests?
A foam roller is a popular technique that in theory should improve range of motion and therefore is something that could be used prior to training. This study showed that for a single session of foam rolling there was no benefit for ITB pain, but that there was an increase in range of motion. In this study, the authors set out “to determine whether foam rolling could improve recovery metrics such as muscle soreness, fatigue, and performance in basketball players after a match”.
STUDY DETAILS
Thirteen female basketball players participated in the study, completing two simulated matches.
Participants used either foam rolling (FR) or a placebo (CON) as the post-match recovery intervention.
Recovery metrics, including countermovement jump height (CMJ), heart rate variability (Ln-rMSSD), muscle soreness (VAS), perceived recovery (TQR), and fatigue (Rating-of-Fatigue), were measured at four time points: pre-match, post-match, post-recovery, and 24 hours post-match.
No significant differences were found between the FR and CON interventions for any recovery variable.
Significant time effects showed lower CMJ and Ln-rMSSD post-match, increased muscle soreness (VAS) after the match, and worsened TQR and fatigue scores from pre- to post-match and pre-match to post-recovery.
PRACTICAL TAKEAWAY
This study suggests that foam rolling does not significantly enhance post-match recovery in female basketball players. I recommend that foam rolling is therefore reserved as a means of increasing range of motion and that it is most likely best used in preparation for a training session rather than using it after training.
PROTEIN: A comparison of dietary protein digestibility, based on DIAAS scoring, in vegetarian and non-vegetarian athletes
In my archives on PROTEIN, I have shared studies that explain the dose and timing of protein intake for muscle protein synthesis. All of these studies consider whey and animal-based protein products. In this study, the authors set out “to determine dietary protein quality using the DIAAS method in vegetarian and omnivore endurance athletes”.
STUDY DETAILS
The study included 38 omnivores and 22 vegetarians.
Participants submitted seven-day food records for nutrient analysis.
The study duration included the seven-day period of food record submission.
DIAAS scores were calculated to determine available protein; lean body mass and leg extension peak torque were measured.
Omnivores had higher DIAAS scores (+11%) and available protein (+43%). They also had higher lean body mass (+14%). Positive correlations were found between available protein and both strength (r=0.314) and lean body mass (r=0.541).
PRACTICAL TAKEAWAY
This study suggests that vegetarian athletes may need to consume an additional 10g of protein daily to meet the recommended intake of 1.2g/kg/day. To achieve the upper recommended intake of 1.4g/kg/day, an additional 22g of protein daily may be required. My recommendation for vegetarian athletes is to follow these guidelines and keep these ideas in mind when planning their macronutrient needs and goals.
STRENGTH: Resistance-only and concurrent exercise induce similar myofibrillar protein synthesis rates and associated molecular responses in moderately active men before and after training
In the studies on STRENGTH in my archives there are studies showing the benefits for running economy and injury prevention for runners. However, many endurance athletes worry about an interference between their strength and endurance goals. In this study, the authors set out to investigate “whether concurrent aerobic and resistance exercise affects myofibrillar protein synthesis (MyoPS) compared to resistance-only exercise”.
STUDY DETAILS
25 moderately active men, divided into three groups: RE-only (n=8), RE plus high-intensity interval exercise (RE+HIIE, n=8), or HIIE+RE (n=9).
3 days/week for 10 weeks, with concurrent sessions separated by 3h.
Muscle samples taken immediately before, after, and 3h post-exercise on Weeks 1 and 10, and analysed for MyoPS and muscle glycogen using deuterium oxide (D2O).
MyoPS rates were similar across all groups in both weeks. Post-exercise protein changes reflective of protein synthesis were also consistent, despite some exercise order-dependent mRNA responses.
After 10 weeks, MyoPS rates and some molecular responses were reduced compared to initial measurements, but concurrent exercise did not negatively impact the anabolic response to RE.
PRACTICAL TAKEAWAY
This study showed that concurrent aerobic and resistance exercise does not impair the muscle-building effects of resistance-only exercise, regardless of exercise order. This means that athletes can include strength in their training plan without worrying about this negatively impacting their endurance training. My recommendation is for athletes to periodise their strength training plan over the season to support their endurance goals without worrying about the strength distracting from these goals.
Quick summary from last week’s paid newsletter
Paid subscribers receive a newsletter every week and have full access to all newsletters listed in the archives (395 studies and practical takeaways). Last week, the newsletter covered studies on the following topics:
Periodization of nutrition in elite female and male runners and race walkers
Quantitative analysis of 92 12-week sub-elite marathon training plans
Effect of 6-week sprint training on long-distance running performance
Sodium bicarbonate for endurance performance
Comparative effects of advanced footwear technology on running economy