RESEARCH: Studies from 24 to 30 June 24
Sharing research and insights from coaches, scientists and athletes to help us improve endurance performance.
Starting this month, I have updated the format of the newsletter slightly.
In the title for each study there are two links: the first link in the category name will take you to that category in the archives; and the second link is the title of the study which will take you to the source of the study.
The second change is that instead of mentioning related studies in the introduction, I have included a related links section after the practical takeaway. Following a link there will take you to the newsletter in which I first shared the study.
This week’s quick summary:
Effect of a graded running race on lower limb muscle damage
Monitoring fatigue state with heart rate-based and subjective methods
No additive effect of creatine, caffeine, and sodium bicarbonate on intense exercise
Absence of neocytolysis after returning from a 3-week high-altitude sojourn
Regular changes in foot strike pattern during prolonged downhill running
RECOVERY: Effect of a graded running race on lower limb muscle damage, jump performance and muscle soreness in men and women
Understanding recovery after a race is important to help plan the training that follows in the pursuit of the next race goal. In particular, muscle damage from a trail race with lots of descent can require longer recovery periods. In this study, the authors set out “to investigate the delayed structural and functional recovery in male and female recreational runners post-race".
STUDY DETAILS
Thirteen female and 14 male recreational runners participated, completing the 20km race and three test sessions: before (PRE), on Day 1 or 2 (D1-2), and on Day 3 or 4 (D3-4).
Muscle damage was assessed via ultrasonography to measure changes in cross-sectional area (CSA) of ten lower-limb muscles.
DOMS was evaluated for three muscle groups, peaking at D1-2 and resolving by D3-4 for all participants.
Functional recovery was measured using kinetic analysis of squat jump (SJ) and drop jump (DJ) tests on a sledge ergometer, with performances declining until D3-4.
Positive and negative correlations between structural and functional changes were found, varying by muscle and sex, with notable differences in the biceps femoris for women and semimembranosus for both sexes.
PRACTICAL TAKEAWAY
This study showed that there was delayed structural and functional muscle recovery after a race and that this recovery was not complete four days after the race. This was despite delayed onset muscle soreness (DOMS) being resolved in one to two days after the race. There were some differences in structural damage between men and women with women presenting damage in hamstring muscles while this was not present for men. My recommendation is to plan a period of recovery of five to seven days post race and not to rely on sensations of muscle soreness to guide recovery.
RELATED RESEARCH
FATIGUE: Monitoring fatigue state with heart rate-based and subjective methods during intensified training in recreational runners
The process of training requires a stimulus and recovery to allow for the body to adapt and improve. However, knowing when to allow for recovery and when to push is not easy to identify and athletes can end up in an overreached state that is counterproductive to development as an athlete. In this study, the authors set out “to investigate the sensitivity and validity of HR-based and subjective monitoring markers in identifying different fatigue states”.
STUDY DETAILS
24 recreational runners were divided into overreached (OR, n=8) and responders (RESP, n=12) based on performance and recovery.
A 3-week baseline period, 2-week overload period, and 1-week recovery period was observed.
Participants’ performance was assessed with a 3000m running test, daily orthostatic tests, nocturnal HR recordings, questionnaires, and exercise data.
RESP improved their 3000m time by -2.5±1.0% post-overload; OR showed a 0.6±1.2% change.
Nocturnal HR, HR variability, readiness to train, and leg soreness differed significantly between RESP and OR subgroups, with nocturnal HR and subjective assessments showing ≥85% predictive values for fatigue.
PRACTICAL TAKEAWAY
This study showed that for recreational runners, monitoring nocturnal HR and subjective recovery assessments like readiness to train and leg soreness can effectively identify fatigue. The authors explained that objective measures like HR were more sensitive to overload than subjective measures, but suggested that in combination these measures were most effective. My recommendation is for athletes to take a daily, morning measurement of HRV and HR, and to note how they feel and what their levels of motivation are. Over time, understanding these metrics and how they vary can be used to help guide training.
RELATED RESEARCH
SUPPLEMENT: No additive effect of creatine, caffeine, and sodium bicarbonate on intense exercise performance in endurance-trained individuals
There are a few supplements that have convincing evidence of performance benefits. Caffeine and creatine are the top of the list and have a place in athletes’ nutrition regimes. However, there has not been much research to support whether the benefits from these supplements are cumulative. In this study, the authors set out “to investigate the potential additive effects of creatine, caffeine, and sodium bicarbonate on athletic performance”.
STUDY DETAILS
The participants were 12 endurance-trained males and 11 females.
Participants were randomized to a 5-day creatine loading phase (0.3g/kg/day) or placebo, followed by a maintenance dose (0.04g/kg/day).
After the loading period, participants completed four trials with different supplement combinations.
Participants ingested caffeine (3mg/kg), sodium bicarbonate (0.3g/kg), placebo, or both before performing a maximal voluntary contraction, a 15-second sprint, and a 6-minute time trial.
Creatine increased mean power output during the 15-second sprint by 34W compared to placebo. Caffeine improved power output in the 6-minute time trial by 12W. Sodium bicarbonate and creatine had no significant effect on the time trial performance.
PRACTICAL TAKEAWAY
The authors explained that “while creatine monohydrate and caffeine respectively enhanced 15-s sprint and 6-min time trial performance, there was no additive, synergistic, or attenuated effect of co-ingesting caffeine and creatine monohydrate on exercise performance”. This suggests that athletes should choose which supplements may be beneficial for them depending on what their goal races are. For most endurance athletes, my recommendation would be to use caffeine to aid in their races. There may be some benefit to using creatine during a strength training phase in the off-season, but it won’t add to performance taken together with caffeine during the race season.
RELATED RESEARCH
Effects of moderate exercise on the pharmacokinetics of caffeine
Creatine supplementation and endurance performance: surges and sprints to win the race
ALTITUDE: Absence of neocytolysis in humans returning from a 3-week high-altitude sojourn
For athletes aiming to perform at sea level after a period at altitude, the timing of competition after the altitude block is important to plan well. Waiting too long may result in the benefits from altitude training being lost before a race. In this paper, the authors “performed a prospective study on erythrocyte survival after a stay at the Jungfraujoch Research Station (JFJRS; 3450m)”.
STUDY DETAILS
Twelve male subjects with a mean age of 23.3 years were studied.
Participants ingested 13C2- and 15N-labelled glycine to age cohort label erythrocytes at 110m and during a 19-day high-altitude stay at 3450m.
The study measured erythrocyte survival and related variables over the high-altitude stay and subsequent descent.
Isotope ratio mass spectrometry of haemoglobin (Hb), total Hb mass (tot-Hb), reticulocyte counts, erythrocyte membrane protein 4.1a/4.1b ratio, and mathematical modelling were used.
Tot-Hb increased by 4.7%±2.7% at high altitude and normalised within 11 days post-descent. Elimination dynamics of labelled erythrocytes were similar regardless of altitude. Erythropoietin levels and CD71-positive reticulocyte counts dropped rapidly after descent, while the 4.1a/4.1b ratio decreased at altitude, remained low for 3-4 days post-descent, and normalised slowly. No haemolysis was observed.
PRACTICAL TAKEAWAY
The results of this study show that for individuals acclimatising to high altitudes, total haemogolbin mass will increase but return to normal within about 11 days after descending. It seems that the increase in young erythrocytes lasted 3-4 days post return from altitude. This finding suggests that aiming to race 3-4 days after returning from altitude is probably optimal. My recommendation for athletes is to plan their taper and return from altitude together to ensure that they are both fresh (from a reduced training load) and that they race early enough to make the most of the benefits from the time at altitude. This most likely requires beginning the taper during the final week at altitude.
RELATED RESEARCH
Periodization of altitude training: A collective case study of high-level swimmers
Variability in hemoglobin mass response to altitude training camps
DOWNHILL: Regular changes in foot strike pattern during prolonged downhill running do not influence neuromuscular, energetics, or biomechanical parameters
In trail races with significant ascents and descents, running fast on the downhills is critical to performing well. However, in longer races the amount of descent can cause muscle damage and leg pain (as explored in the first study above). In this study, the authors set out “to investigate whether a strategy with regular changes in foot strike pattern during downhill running could reduce the extent of fatigue on neuromuscular, energetics and biomechanical parameters”.
STUDY DETAILS
Fourteen experienced trail runners participated in the study.
Participants completed two 2.5-hour treadmill running sessions with and without alternating foot strike patterns every 30 seconds during downhill sections.
The sessions were separated by 15 days in a pseudo-randomised, counter-balanced order.
Neuromuscular tests assessed PF fatigue, indirect calorimetry measured energy cost, and an instrumented treadmill recorded biomechanical gait parameters.
No significant differences in fatigue, energy cost, or time-to-exhaustion (TTE) were found between the two conditions.
PRACTICAL TAKEAWAY
The results of this study suggest that trail runners might not benefit from deliberately alternating foot strike patterns to reduce fatigue. Instead, adapting foot strike patterns to match the terrain could enhance running technique and performance. My recommendation is for athletes to focus on downhill training and performing downhill repeats to prepare for downhills rather than trying to change their technique to reduce the impact of descents.
RELATED RESEARCH
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 (405 studies and practical takeaways). Last week, the newsletter covered studies on the following topics:
A sprained ankle is the biggest sign of mental fatigue
The need for multiple trials in assessing RE responses in supershoes
The impact of 48h high carbohydrate diets with high and low FODMAP content
Whole-body energy metabolism in iron-deficient athletes
Refuting the myth of non‐response to exercise training