RESEARCH: Studies from 4 to 10 Mar 24
Sharing research and insights from coaches, scientists and athletes to help us improve endurance performance.
This week’s quick summary:
Higher fraction of VO2 Max during intervals improves performance
Effects of acute sleep loss on physical performance
The athletic gut microbiota
Monitoring athletes during training camps
Exercise and mitochondrial health
TRAINING: The higher fraction of VO2 Max during interval training, the greater gains in performance
In my intervals training archives there are studies that show the impact of different forms of interval training on VO2 Max. In this study, the authors set out “to investigate the importance of average fraction of VO2 Max achieved during HIT sessions (%VO2max HIT) throughout a nine-week exercise training intervention on changes in endurance performance and physiological determinants of endurance performance in cyclists”.
STUDY DETAILS
Twenty-two participants (3 female and 19 male) underwent a nine-week exercise intervention involving 20.6 ± 0.8 sessions, each comprising 5x8-min intervals at 40-min maximal power output.
VO2 was continuously measured during work periods (average %VO2maxHIT, 83.0 ± 5.0%). Physiological tests were conducted before and after the intervention, including a blood lactate profile, VO2 Max test, and a 15-min time trial.
Positive correlations were found between %VO2maxHIT and changes in Wmax, PO@4mmol (power output), and the performance index.
Theoretical estimates suggest that increasing %VO2maxHIT from 80 to 90% during a similar nine-week intervention could lead to additional improvements in Wmax, PO@4mmol, and the performance index.
There was no observed relationship between %VO2maxHIT and changes in PO@15min or gross efficiency at 175 watts, but a positive relationship was noted with changes in VO2 Max and fractional utilization of VO2 Max at 4 mmol·L-1[La-].
PRACTICAL TAKEAWAY
This study suggests that incorporating HIT sessions designed to achieve a high %VO2maxHIT could be an effective strategy for enhancing endurance performance. In the study the authors used 8’ intervals, however this may take some time to build up to. My recommendation is for athletes to start with intervals of shorter duration (4-5 x 3’) and then build up to longer intervals when they are able to extend the time at which they can hold a higher intensity. The goal of these interval training sessions should be to achieve the intensity first, then extend the duration at intensity.
SLEEP: Effects of acute sleep loss on physical performance
The studies I have shared on sleep (see the sleep archives) show that sleep deprivation can have significant impacts on performance and even on issues such as gastrointestinal symptoms. In this review, the authors set out to show that the “impact of sleep loss on physical performance is critical for individuals involved in athletic pursuits”.
REVIEW DETAILS
The authors analyzed 227 outcome measures from 69 publications to assess the impact of sleep loss on exercise performance.
They found a negative impact of sleep loss across all exercise categories.
Consistent negative effects were observed with deprivation and late-restriction sleep loss protocols.
Performance in tasks performed in the evening showed greater impairment compared to those in the morning.
A significant positive relationship was noted between time awake prior to exercise and the decrease in performance for both deprivation and late-restriction protocols.
PRACTICAL TAKEAWAY
The results of this review showed that sleep loss negatively affects exercise performance. To mitigate this, the authors recommend prioritising adequate sleep, but if sleep loss is unavoidable to schedule exercise in the morning.
PHYSIOLOGY: The athletic gut microbiota
This is the first review that I’ve seen that looked into the gut microbiota of athletes in particular. The authors set out “to explore the influence of exercise and associated factors on the gut microbiota, particularly in high-level athletes, with a focus on its implications for health and sports performance”.
REVIEW DETAILS
High-level athletes demonstrate unique physiology and metabolism, potentially impacting their gut microbiota.
Exercise and associated factors such as sport-specific diet and environment contribute to shaping the gut microbiota.
Athletic classification correlates with a more "health-associated" gut microbiota.
Characteristics of this health-associated microbiota include higher abundance of beneficial bacteria and increased microbial diversity.
The gut microbiota of athletes exhibits improved gastrointestinal barrier function and stimulation of bacterial abundance that can modulate mucosal immunity.
PRACTICAL TAKEAWAY
The authors suggest that cultivating a health-associated gut microbiota through exercise and appropriate dietary choices may contribute to improved sports performance and overall well-being. Two important points the authors make which are my takeaways from this study revolve around protein: “Protein intake appears to be a strong modulator of microbiota diversity, with protein supplementation, such as whey, showing potential benefits…Proteins from vegetable origin have a marked effect on gut microbiota but currently require investigation in athletes”. My recommendation is to read the paper in full to understand the impact of athletes’ training and diet on their microbiota and to maintain high levels of aerobic exercise and adequate protein intake to ensure microbiota diversity.
TRAINING: Monitoring athletes during training camps: observations and translatable strategies from elite road cyclists and swimmers
Monitoring training load is a challenge. I have a whole section in my archives on training load and most of the studies show that “no single measure has been identified that can accurately quantify the fitness and fatigue responses to training or predict performance”. In this paper the authors reviewed the practices of elite athletes “to unveil typical measurements and responses observed in elite road cyclists and swimmers during training camps, translating these findings into practical strategies”.
STUDY DETAILS
Twenty-nine male professional cyclists and 31 male and female international swimmers participated in up to three 4–19 day training camps.
Monitoring encompassed body mass, composition, subjective sleep, urinary specific gravity (USG), resting heart rate (HR), and peripheral oxygen saturation (SpO2) at altitude.
Sum of seven skinfolds decreased by 3.1 ± 3.6 mm weekly, with body mass decreasing by 0.4 ± 0.4 kg.
At altitude, sleep quality slightly improved (0.3 ± 0.3 AU), SpO2 possibly increased (0.6 ± 1.7%), while changes in resting HR were uncertain (0 ± 4 bpm).
Sleep duration and USG remained stable. Monitoring individual vs. group changes can identify athletes at risk of training maladaptation.
PRACTICAL TAKEAWAY
This study advocates for a comprehensive approach to monitoring elite athletes during training camps. Similar to the point I shared in the introduction to this study, the authors explain that “to date, there is no single measure which can be used in isolation for athlete monitoring”. My takeaway and recommendation aligns with the conclusion in the paper which recommends that the “greatest utility is subjective wellbeing, which may be supplemented by other subjective and objective measures”.
PHYSIOLOGY: Exercise and mitochondrial health
Most athletes and coaches recognise that one of the intentions in performing aerobic exercise is to increase mitochondria numbers and to improve mitochondrial health. In this review, the authors look into this in detail: “With skeletal muscle as a model, this study explores mitochondrial adaptations, particularly under exercise, vital for metabolic health across diseases and aging”.
REVIEW DETAILS
Mitochondria exhibit remarkable plasticity, adjusting volume, structure, and capacity during exercise.
Muscle mitochondria form a dynamic reticulum maintained by biogenesis, fusion, fission, and mitophagy.
Understanding these processes could unveil therapeutic targets for health and longevity.
Investigating convenient exercise modalities may promote widespread mitochondrial health improvements.
Exercise remains the most potent means to enhance mitochondrial health, not only in muscle but potentially in other tissues.
PRACTICAL TAKEAWAY
This review shows that regular exercise offers profound benefits for mitochondrial health, potentially extending to overall well-being and longevity. This is probably not a revelation for most athletes, however, it is a good reminder of the important of regular exercise and its benefit for mitochondrial health and aerobic performance. Keep “training for life”.
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 (over 300 studies and practical takeaways). Last week, the newsletter covered studies on the following topics:
Role of beetroot consumption on recovery for endurance runners
Changes in economy and fractional use of VO2peak at altitude
Habitual caffeine consumption and the ergonomic benefits of caffeine
Direct and indirect impact of LEA on sports performance
The impact of a 40-min nap on neuromuscular fatigue profile and recovery