RESEARCH: Studies from 25 Nov to 1 Dec 24
Sharing research and insights from coaches, scientists and athletes to help us improve endurance performance.
This week’s quick summary:
Predicting physiological and haematological response to altitude training
Time-course for onset and decay of heat acclimation training
Effects of a 7-day overload-period of high-intensity training
Chronic psychological stress impairs recovery over a 96-hour period
The effect of elevated muscle pain on neuromuscular fatigue during exercise
ALTITUDE: Predicting an athlete’s physiological and haematological response to live high-train high altitude training using a hypoxic sensitivity test
Live high-train high (LHTH) altitude training is a popular strategy among elite endurance runners to enhance sea-level performance. However, individual responses to hypoxic exposure vary, leading to inconsistent findings. This study aimed to “document changes in total haemoglobin mass (tHbmass) and physiological capacity following a 4-week LHTH intervention, and to assess whether a hypoxic sensitivity test (HST) could predict these adaptations”.
STUDY DETAILS
15 elite athletes participated in a 4-week LHTH training camp at approximately 2400m altitude.
Measurements included lactate threshold (LT), lactate turn point (LTP), maximal oxygen uptake (VO2 Max), and tHbmass, taken before and after the intervention.
Daily physiological measures (arterial oxygen saturation and body mass) and subjective wellbeing were recorded during the camp.
Athletes completed an HST prior to the LHTH intervention.
Results showed significant improvements in average tHbmass (1.8%), VO2max (2.7%), LT (6.1%), and LTP (5.4%) after the 4-week LHTH camp.
PRACTICAL TAKEAWAY
This study suggests that a hypoxic sensitivity test can help predict individual changes in tHbmass and VO2max. This could allow for more personalised acclimatisation strategies and training load management during altitude exposure. My recommendation for athletes going to altitude is to put in place means of performance measurement for before and after the altitude sojourn (this could be an HST or field tests), and to use daily metrics (such as SpO2 and HRV) while at altitude to adjust training based on each athlete’s rate of acclimation.
RELATED RESEARCH
HEAT: Time-course for onset and decay of physiological adaptations in endurance trained athletes undertaking prolonged heat acclimation training
Heat acclimation (HA) is a crucial strategy for athletes to improve performance in hot conditions. In this study, the authors set out "to establish the time-course for physiological adaptations and performance effects of completing 5 weeks of HA (six one-hour HA-training sessions per week)”.
STUDY DETAILS
20 male elite cyclists participated, with 10 in the intervention group (HEAT) and 10 in the control group.
The intervention involved 5 weeks of heat acclimation, with six one-hour HA-training sessions per week.
Measurements included time to exhaustion, sweat rate, sweat sodium concentration, total haemoglobin mass, and incremental peak power output.
HEAT group improved time to exhaustion by 15 minutes, increased sweat rate by 0.44L/hour, and lowered sweat sodium concentration by 14.1mmol/L after HA.
Total haemoglobin mass increased by 30 grams after 3 weeks and 40 grams after 5 weeks, while incremental peak power output improved by 12W.
PRACTICAL TAKEAWAY
This study showed that 5 weeks was superior to 3 weeks of heat acclimation and that after stopping heat acclimation the adaptations were significantly reversed within 2 weeks. This helps to create guidelines for heat adaptation. My recommendation for athletes is to plan a period of at least 5 weeks before their key race to implement a heat acclimation protocol and to maintain this right up until a few days before the race. In this study the protocol was 6 one-hour heat acclimation sessions per week. If athletes have capacity to do a longer period of heat acclimation (8-10 weeks), I believe that after the first 5 weeks, maintaining ~3 sessions per week should maintain the acclimation benefits.
RELATED RESEARCH
TRAINING: Effects of a seven day overload-period of high-intensity training on performance and physiology of competitive cyclists
Athletes often engage in intense training periods before major competitions to enhance their performance. Another possible training situation would be a set of crash training for athletes who have missed training in the key period before their race. This study aimed to “investigate the effects of two different seven-day high-intensity overload training (HIT) regimes on cyclists' performance and physiological characteristics”.
STUDY DETAILS
28 male cyclists (average age 33 years, mass 74kg, VO2 peak 4.7L·min−1) were divided into a control group and two training groups.
The HIT sessions lasted about 120 minutes and involved maximal intensity efforts of either 5, 10, and 20 seconds (short) or 15, 30, and 45 seconds (long).
Cyclists completed an incremental exercise test and a 20km time-trial before and after the training period.
Both short and long HIT regimes resulted in significant improvements in time trial performance compared to the control group, with mean power increases of 8.2% and 10.4% respectively.
The HIT interventions led to non-significant increases in VO2 peak, lactate threshold power, and gross efficiency, with only small differences between the short and long regimes.
PRACTICAL TAKEAWAY
This study suggests a 7-day overload training period can be effective. There is obviously plenty of risk involved in following this approach so my recommendation would be to consider it only under specific circumstances. First, for athletes in race season who are fit, but have struggled to find consistency in the season, a block of overload training could be effective to boost their performance for later races. Second, for athletes who have missed training and are willing to take a risk, they could try to fit in a final block of training 2-3 weeks prior to a race. Finally, for anyone considering this, it is important to allow enough time after the block to recover fully and adapt to that overload period.
RELATED RESEARCH
PSYCHOLOGY: Chronic psychological stress impairs recovery of muscular function and somatic sensations over a 96-hour period
I believe that the body does not distinguish between different forms of stress and that all individuals have a limit of what they can cope with. This means for athletes aiming to perform well, they need to reduce lifestyle stress to accommodate more training stress. This study aimed to “investigate whether chronic mental stress moderates recovery of muscular function and somatic sensations: perceived energy, fatigue, and soreness, in a 4-day period after a bout of strenuous resistance exercise".
STUDY DETAILS
Participants were 31 undergraduate resistance training students with an average age of 20.26 years.
Students completed stress questionnaires and later performed a heavy-resistance exercise protocol involving leg press exercises.
Maximal isometric force, perceived energy, fatigue, and soreness were assessed at 24 hour intervals for 4 days post-exercise.
Life event stress significantly moderated the recovery of maximal isometric force, perceived energy, fatigue, and soreness.
Higher stress levels were consistently associated with worse recovery across all measured variables.
PRACTICAL TAKEAWAY
This study showed that athletes with high levels of life stress took significantly longer to recovery from heavy training. My recommendations are two-fold:
For athletes going into a block of important training, aim to reduce life stress and plan the block with the aim of making training a significant focus;
For athletes with high life stress, allow more time to recover from training of up to 4 days after big sessions.
RELATED RESEARCH
FATIGUE: The effect of elevated muscle pain on neuromuscular fatigue during exercise
The relationship between muscle pain, perception of effort, and fatigue is something athletes know about, but the mechanisms are not yet clear. In this study, the authors aimed to “investigate how muscle pain affects neuromuscular fatigue during an endurance task”.
STUDY DETAILS
12 participants completed isometric time-to-task failure (TTF) exercises of the right knee extensors at 20% of maximum force.
Participants received intramuscular injections of isotonic saline (control) or hypertonic saline (experimental) into the vastus lateralis.
Neuromuscular fatigue was measured using transcranial magnetic stimulation and peripheral nerve stimulation.
Pain intensity was significantly higher in the hypertonic saline condition, and TTF was reduced by 16% compared to the control condition.
Maximum voluntary force and voluntary activation were lower in the hypertonic saline condition, and the TMS silent period was longer.
PRACTICAL TAKEAWAY
This study showed that muscle pain can significantly reduce exercise performance by exacerbating neuromuscular fatigue. Therefore, in order to optimise performance, strategies to manage and minimise muscle pain during training and competition should be considered. My recommendation for athletes is to implement race-specific sessions into their training to prepare them for the demands (and potential muscular pain) of a race. Then, pain management techniques or methods to reduce perception of effort can be employed during the race. These can include good warm-ups, cooling during hot races, mental techniques and mantras, and having good support at the race.
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 (515 studies and practical takeaways). Last week, the newsletter covered studies on the following topics:
Collagen supplementation does not increase connective tissue synthesis rates
Lactate kinetics at the lactate threshold in trained and untrained men
Midsole hardness and surface type effect on landing impact in heel-strike runners
Do probiotics mitigate GI-induced inflammation and perceived fatigue?
The influence of pre-race sleep and training profiles on performance
