RESEARCH: Studies from 19 to 25 Aug 24
Sharing research and insights from coaches, scientists and athletes to help us improve endurance performance.
This week’s quick summary:
Influence of supershoes for competitive female runners
Perspectives on altitude camps and heat acclimation training
Responses during exertional heat stress after antihistamine use
Sleep hygiene can improve performance following long-haul air travel
The effects of continuous compared to accumulated exercise on health
EQUIPMENT: The influence of “super-shoes” and foot strike pattern on metabolic cost and joint mechanics in competitive female runners
Supershoes have proven to be beneficial for improving road-running performance in certain populations and I recommend supershoes to anyone aiming to achieve their best possible times in a road race. However, as these shoes are still relatively new, there is ongoing research into how they benefit different populations. In this study, the authors set out “to assess the influence of ‘super-shoes’ on metabolic cost and joint mechanics in competitive female runners and to understand how foot strike pattern may influence the footwear effects”.
STUDY DETAILS
18 competitive female runners were included in the study.
Each runner completed four 5-minute runs on a force-instrumented treadmill at a speed of 12.9km/h, wearing either Nike Vaporfly Next% 2™ (SUPER) or Nike Pegasus 38™ (CON) shoes.
Each run lasted 5 minutes, and the shoes were tested in a randomised and mirrored order.
Metabolic power and joint mechanics (MTP, ankle) were measured during the runs.
Metabolic power improved by 4.2% in SUPER shoes. Joint mechanics showed reduced negative and positive work at the MTP and ankle in SUPER shoes. Foot strike pattern did not influence the metabolic benefits of the shoes.
PRACTICAL TAKEAWAY
This study showed that for competitive female runners, supershoes can improve performance by as much as 4%. Foot strike pattern does not affect these benefits, suggesting that runners can experience performance improvements regardless of their natural running style. My recommendation for competitive road runners therefore remains the same: all runners hoping to perform their best should use supershoes.
RELATED RESEARCH
Recreational runners gain physiological and biomechanical benefits from supershoes at marathon paces
HEAT and ALTITUDE: High or Hot – Perspectives on altitude camps and heat acclimation training as preparation for prolonged stage races
Environmental factors can be both a race-specific demand to prepare for and a stimulus to use to develop certain aspects of an athlete’s physiology. Heat and altitude are the two most common aspects to consider. In this study, the authors set out to “provide guidance based on our experience from practical implementation in cyclists preparing for prolonged stage races such as the Tour de France”.
STUDY DETAILS
20 elite cyclists participated in the study, undergoing either altitude training, heat acclimation, or a combination of both.
The intervention lasted 3 weeks, with athletes exposed to moderate hypoxia (2000-2500m altitude) or high temperatures (35°C) during their regular training sessions.
Haemoglobin mass and arterial oxygen saturation were measured before and after the intervention to assess physiological changes.
Heat acclimation resulted in significant improvements in thermoregulatory capacity, including increased plasma volume and improved sweat response.
Combining hypoxia and heat exposure led to enhanced respiratory adaptations, improving arterial oxygen saturation during altitude exposure.
PRACTICAL TAKEAWAY
This study showed that both heat and altitude provide stimuli that results in adaptations by the athletes. This is consistent with all the previous research that shows the benefits of heat and altitude training (see the studies I’ve shared by clicking on the links in the heading of this section). However, the authors note that it may not be cumulative with benefits from both heat and altitude being achieved at the same time if an athlete goes on a heat and altitude training camp; this could be difficult practically as not many altitude locations above 2000m have temperatures of 35C. My recommendation for athletes is to select the stimulus that is most specific to their race and to prioritise that in their preparation. If they want to use both heat and altitude, I recommend alternating hot and high training camps rather than trying to use both stimuli simultaneously.
RELATED RESEARCH
SUPPLEMENT: Thermal and cardiovascular responses during exertional heat stress after diphenhydramine use
At the beginning of the race season in the early summer, many athletes suffer from allergies and look to using antihistamines to help with the symptoms. However, there is limited systematic evidence to support this practice. In this study, the authors set out “to examine whether diphenhydramine hydrochloride affects the sweating, core temperature, and heart rate response during exertional heat stress”.
STUDY DETAILS
20 healthy adults (10 females, aged 23±3 years) participated in the study.
Participants consumed either 50mg of DPH or a placebo (PLA) in a double-blind randomized crossover design.
After a 2-hour rest in a climate-controlled room (30°C, 35%RH), participants walked on a treadmill for 60 minutes.
Researchers measured whole-body sweat loss (WBSL), local sweat rate (LSR), rectal temperature (Trec), and heart rate (HR).
No significant differences were found between the DPH and PLA groups in WBSL, LSR, Trec, or HR.
PRACTICAL TAKEAWAY
The results of this study show that for healthy adults taking 50mg of diphenhydramine before exercising in hot conditions does not significantly affect sweating, core temperature, or heart rate. My recommendation for athletes is that taking antihistamines for allergies is not something that they should worry about in hot conditions.
RELATED RESEARCH
SLEEP: Sleep hygiene and light exposure can improve performance following long-haul air travel
Sleep is critical to ensure that athletes adapt from the training they perform each day. Prior to races, sleep banking is also an option to help improve performance. However, athletes often have to travel to races and the travel can interrupt their sleep routines. In this study, the authors set out “to determine if implementing sleep hygiene strategies and adjusting light exposure could enhance recovery and performance following long-haul flights”.
STUDY DETAILS
The study involved 60 healthy adults who had recently completed a long-haul flight crossing five or more time zones.
Participants were divided into two groups: one received sleep hygiene and light exposure interventions, while the control group did not.
The intervention lasted for 72 hours post-flight, focusing on regular sleep schedules, minimising screen time before bed, and controlling light exposure (morning bright light and evening dim light).
Performance was measured using cognitive tests, reaction time assessments, and subjective fatigue ratings.
The intervention group showed significant improvements in cognitive performance, faster reaction times, and reduced fatigue compared to the control group.
PRACTICAL TAKEAWAY
The results of this study showed that to optimise performance and reduce fatigue after long-haul flights, athletes should implement sleep hygiene practices such as maintaining a consistent sleep schedule, limiting screen time before bed, and adjusting light exposure by getting bright light in the morning and dimming lights in the evening. The study considered the 3 days after a long-haul flight. My recommendation is for athletes to plan enough time between their travel and race to implement these best practices to ensure they are fresh and ready to race.
RELATED RESEARCH
TRAINING: The effects of continuous compared to accumulated exercise on health
Fitting in training can often be difficult when athletes have other commitments to meet. In this study, the authors set out “to examine if exercise interventions consisting of a single bout of exercise compared with interventions comprising the same total duration, mode, and intensity of exercise accumulated over the course of the day have different effects on health outcomes in adults”.
STUDY DETAILS
The study included 19 studies with a total of 1080 community-dwelling adults.
The interventions compared continuous exercise to accumulated exercise of the same intensity, duration, and mode.
The study periods varied, but all assessed outcomes post-intervention.
Health outcomes such as cardiorespiratory fitness, blood pressure, body mass, body fat percentage, and cholesterol levels were measured.
No significant differences were found in fitness or blood pressure. However, accumulated exercise resulted in slightly better outcomes for body mass reduction, body fat percentage, and LDL cholesterol levels compared to continuous exercise.
PRACTICAL TAKEAWAY
This study looked at the health benefits for adults (not necessarily athletes) in using different training distributions over the day. The authors found that people can achieve similar health benefits from either a single continuous exercise session or multiple shorter bouts throughout the day. I think that it is possible to extend this to athletes and their training. With the exception of race simulations or long runs, I recommend that athletes give themselves the freedom to achieve the most training stimulus they can whether that is through individual sessions or multiple bouts throughout the day.
RELATED RESEARCH
Best Time of Day for strength and endurance training to improve health and performance
The training intensity distribution among well-trained and elite endurance athletes
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 (445 studies and practical takeaways). Last week, the newsletter covered studies on the following topics:
Influence of menstrual cycle and contraceptives on performance
Effect of hypoxia method on repeated sprint ability
Air speed and direction affect metabolic and thermoregulatory responses
Long-term resistance trained human muscles have more fibres
Changes in durability and underlying physiological over a season