RESEARCH: Studies from 2 to 8 Sep 24
Sharing research and insights from coaches, scientists and athletes to help us improve endurance performance.
This week’s quick summary:
Sex-based differences in haematological values
Enhanced time-trial performance with higher-pressure compression garments
Haematological adaptations to training with and without heat
Comparison between one long and two short sessions of intensity training
Is post-exercise muscle soreness a valid indicator of muscular adaptations?
PHYSIOLOGY: Sex-based differences in haematological values after normalization to body mass or fat-free mass in adults matched for aerobic fitness
It is important to individualise training for each athlete and one of the ways that is often considered is differentiating training between male and female athletes. In this study, the authors set out “to investigate whether sex differences in blood properties persist when males and females are matched for aerobic fitness”.
STUDY DETAILS
The study included 45 males and 34 females matched for VO2 Max, normalised to fat-free mass (FFM).
Body composition was measured using dual-energy x-ray absorptiometry (DXA).
Aerobic capacity (VO2 Max) was assessed via an incremental exercise test, while blood properties were measured using a carbon monoxide (CO) rebreathe test.
Females showed higher BV (+4%) and plasma volume (PV) (+14%) than males, but lower red blood cell volume (RBCV) (-8%) and Hbmass (-8%).
Fat mass did not significantly affect blood properties, while FFM was a strong predictor of both BV and Hbmass.
PRACTICAL TAKEAWAY
The results of this study showed that female athletes exhibit greater plasma and blood volumes when matched with males for aerobic fitness, though they have lower red blood cell volume and haemoglobin mass. This suggests that females may rely on different strategies for oxygen delivery and extraction during exercise. It is not easy to make recommendations from this type of high-level research that doesn’t look at mechanisms, however, there are some potential take-aways. I believe that there may be opportunities for female athletes to benefit more from altitude training and so my recommendation would be to try 3-4 week blocks testing red blood cell volume and haemoglobin to assess if there are any changes.
RELATED RESEARCH
EQUIPMENT: Enhanced cycling time-trial performance during multi-day exercise with higher-pressure compression garment wear
Compression garments have mixed evidence with regards to their effectiveness despite their continued popularity. In this study, the authors set out to determine whether or not “increased pressure levels applied via high-pressure compression garments would enhance multi-day exercise performance”.
STUDY DETAILS
Ten trained male cyclists participated in the study.
Participants completed three blocks, each consisting of high-intensity cycling, a 24-hour recovery period wearing one of three garment types (loose, low-compression, or high-compression), followed by an 8-km time trial.
Power output, oxygen consumption, heart rate, plasma lactate, creatine kinase, and myoglobin concentrations were measured throughout.
Results showed improved time-trial performance in the high-compression condition (277W) compared to both low-compression (265W) and loose-fitting conditions (266W).
Plasma lactate levels were significantly lower in the high-compression group at 30 and 60 minutes post-exercise on day 1, with no significant differences in oxygen consumption, heart rate, or discomfort.
PRACTICAL TAKEAWAY
The results of this study suggest that high-pressure compression garments may offer an advantage for performance during competition over multiple days. My recommendation for athletes competing over multiple rounds or days of competition is to use compression between their races. Even if it is just a placebo affect, there could be a benefit and it is worth trying.
RELATED RESEARCH
HEAT: Haematological adaptations to training with and without heat
Heat training is a potential stimulus to help increase the rate of adaptation to training. In this study, the authors set out “to investigate the haematological adaptations associated with a long-term, progressive, work-matched controlled heart rate heat acclimation (HA) protocol”.
STUDY DETAILS
Ten male participants (VO2peak: 4.50±0.50L/min) completed two 3-week interventions, alternating between HA (36°C, 59% RH) and temperate conditions (18°C, 60% RH).
Training consisted of 5 consecutive sessions per week, with 4 controlled heart rate sessions and 1 repeated sprint session, followed by 2 rest days.
Haemoglobin mass dropped by day 4 in HA (-22g) but remained stable in temperate conditions, returning to baseline by the end of the intervention.
HA led to a lower resting heart rate (-4 beats/min) and increased power output (+18W), while no such changes occurred in temperate conditions.
Plasma volume increased similarly in both conditions (+168mL in HA, +166mL in temperate) by day 11 of training.
PRACTICAL TAKEAWAY
The results of this study showed that training in heat also leads to increased power output and whole-body sweat rate. Plasma volume expands with heat or temperate training, but heat offers additional physiological benefits. My recommendation for athletes, especially those planning to race in hot conditions, is to include heat acclimation training camps in their training. In this study, the intervention was a 3-week training camp with 5 repeated sessions per week at 36°C.
RELATED RESEARCH
INTERVALS: Comparison of acute physiological responses between one long and two short sessions of moderate-intensity training in endurance athletes
Double threshold sessions are a popular training method most notably used by the Norwegian athletes. In this study, the authors set out “to better understand the pros and cons of organising moderate-intensity training as one long versus shorter sessions performed more frequently”.
STUDY DETAILS
Fourteen male endurance athletes (VO2 Max: 69.2±4.2mL·min−1·kg−1) participated in the study.
Participants completed two separate moderate-intensity training sessions: a single 6×10-min session (SINGLE) and two 3×10-min sessions (DOUBLE), with 6.5 hours of recovery between the latter.
Heart rate, blood lactate concentration, and perceived exertion increased in the second half of the SINGLE session, while these metrics decreased in the DOUBLE session.
SINGLE led to a higher supine heart rate, session perceived exertion (sRPE), and training load compared to DOUBLE.
The morning after the sessions, perceived fatigue and muscle soreness were higher following SINGLE.
PRACTICAL TAKEAWAY
The results of this study suggest that for endurance athletes, shorter, more frequent training sessions may offer a lower training stress while maintaining similar physiological benefits. Athletes aiming to reduce post-session fatigue and muscle soreness may find two shorter sessions more effective than one long session, without compromising training intensity. My recommendation for athletes who have the ability to schedule multiple sessions in a day, is to consider double threshold sessions to help manage their training load. It is important to remember that this approach split one session into two sessions and that athletes should not try to increase the total time at intensity when performing two sessions.
RELATED RESEARCH
Influence of interval training frequency on time-trial performance in elite endurance athletes
A narrative review exploring advances in interval training for endurance athletes
STRENGTH: Is post-exercise muscle soreness a valid indicator of muscular adaptations?
Many athletes consider how sore their legs feel after a session to judge its effectiveness. In this study, the authors set out “to assess the validity of delayed-onset-muscle soreness (DOMS) as an indicator of muscular adaptation and growth”.
STUDY DETAILS
Participants included individuals of varying fitness levels performing eccentric and concentric resistance exercises.
The intervention lasted several weeks, focusing on novel and familiar resistance training stimuli.
DOMS was measured using visual analogue scales and biomarkers like creatine kinase levels.
Results showed no strong correlation between DOMS intensity and muscle damage or hypertrophy across participants.
Despite soreness, muscle adaptation occurred even in those reporting little or no DOMS, and high levels of soreness negatively impacted performance and recovery.
PRACTICAL TAKEAWAY
The results of this work suggest that DOMS is not a reliable indicator of muscle growth. Individuals can experience hypertrophy without significant soreness. My recommendation for athletes doing strength training is that not every session needs to hurt and result in soreness in the following days to be beneficial. Rather, athletes should follow a well-planned programme and follow principles of progressive overload in their strength training.
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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 (455 studies and practical takeaways). Last week, the newsletter covered studies on the following topics:
Precision of handheld blood lactate analysers
Weighted-jump-squat training for explosive power
Application of the IOC REDs assessment tool in elite athletes
Background inactivity blunts metabolic adaptations to training
Ad-libitum fluid intake was insufficient to achieve euhydration 20h after running