RESEARCH: Studies from 16 to 22 Sep 24
Sharing research and insights from coaches, scientists and athletes to help us improve endurance performance.
This week’s quick summary:
Effects of foot-strike pattern on neuromuscular function during running
No effect of a carbohydrate-menthol drink on thermal perceptual measures
Hamstrings hypertrophy is specific to the training exercise
Muscle glycogen storage after different amounts of carbohydrate ingestion
Physiological effects of tapering and detraining in world-class kayakers
PHYSIOLOGY: Effects of foot-strike pattern on neuromuscular function during a prolonged graded run
Trail runners often wonder whether a particular foot-strike pattern is optimal for different terrain or different grades. Is a rear-foot-strike (RFS) pattern or non-RFS superior? In this study, the authors set out “examine if a dominant foot-strike pattern affects neuromuscular fatigue after a prolonged graded run”.
STUDY DETAILS
16 experienced male trail runners, split into 8 non-RFS and 8 RFS, participated in the study.
The intervention involved a 2.5-hour graded treadmill run.
Neuromuscular fatigue of the plantar flexors was tested before and after the run.
Biomechanical gait parameters were recorded using an instrumented treadmill.
Results showed no significant difference between the groups in terms of neuromuscular fatigue, muscle activation, or biomechanical measures.
PRACTICAL TAKEAWAY
The results of the study suggest that foot-strike patterns, whether non-RFS or RFS, do not appear to influence neuromuscular fatigue after prolonged graded running. Therefore, runners do not need to change their running form and should do what feels best to them. My recommendation is not to worry about foot-strike pattern and focus on moving efficiently and effectively through the terrain.
RELATED RESEARCH
SUPPLEMENT: No effect of a commercial carbohydrate-menthol drink on thermal perceptual measures or 15-min time trial performance compared to commercial carbohydrate drink in hot humid conditions
When racing in hot conditions it is important to acclimate prior to the race and also to have strategies for during the race to cope with the conditions. One way to deal with the heat is to have cooled drinks or to use slushies to lower core temperature. In this study, the authors set out “to assess whether adding menthol to a carbohydrate drink could improve time trial performance and comfort levels in cyclists”.
STUDY DETAILS
10 participants (5 women) with an average VO2 Max of 52.3mL/kg/min completed two trials under hot (35°C) and humid (54%) conditions.
Each trial included a 40-min preload (50% VO2 Max) followed by a 15-min self-paced time trial. Drinks were swilled and ingested every 10 minutes.
Heart rate, rectal temperature, thermal sensation, thermal comfort, and perceived exertion were recorded regularly.
No significant difference in total work (kJ) was found between the carbohydrate (153kJ) and carbohydrate-menthol (151kJ) drinks.
Participants preferred the taste and aftertaste of the carbohydrate-only drink over the menthol version.
PRACTICAL TAKEAWAY
The results of this study showed that cyclists performing in hot, humid conditions may not experience any added performance or comfort benefit from a carbohydrate-menthol drink compared to a carbohydrate-only drink. My recommendation is that athletes do not need to seek out drinks with menthol in them to help with hot conditions. However, if an athlete likes the taste and has a drink with menthol in it, there is no harm in continuing to use it.
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STRENGTH: Hamstrings hypertrophy is specific to the training exercise: Nordic hamstring versus lengthened state eccentric training
Runners often include strength training in their training plans to improve running economy and to reduce injury risk. As strength training is a complement to running training, it is important to choose the most effective exercises to maximise the benefit while reducing time needed for this training. In this study, the authors set out “to compare two eccentric knee flexion training methods - Nordic hamstring training (NHT) and lengthened state eccentric training (LSET) - to determine which training method yields greater muscle size and strength adaptations”.
STUDY DETAILS
42 healthy males, split into three groups: NHT, LSET, and a control group (CON), participated in the study.
The training intervention lasted 12 weeks, with 34 sessions for both NHT and LSET groups.
Magnetic resonance imaging measured the volume of knee flexor muscles and BFlh aponeurosis area before and after the intervention.
LSET showed greater increases in hamstring (+18% vs +11%) and BFlh (+19% vs +5%) muscle volumes, as well as BFlh aponeurosis area (+9% vs +3%) compared to NHT.
Maximum eccentric torque improved more in LSET (+17%) compared to the control group (+4%), with NHT showing a moderate increase (+11%).
PRACTICAL TAKEAWAY
The results suggest that LSET may be more effective than NHT as LSET not only increases muscle size in key sprinting muscles but also improves torque output, which could reduce the risk of hamstring strains. My recommendation for athletes is to use lengthen-state eccentric training for their hamstrings. In the study the athletes started with 2 sets of 6 reps twice a week, then built up to 4 sets of 10 reps twice a week over a 12-week period.
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PHYSIOLOGY: Muscle glycogen storage after different amounts of carbohydrate ingestion
Post-exercise recovery usually focuses on protein intake, but it is also important to include carbohydrate during this period to restore muscles glycogen. In this study, the authors set out “to determine whether the rate of muscle glycogen storage could be enhanced during the initial 4h period post-exercise by substantially increasing the amount of carbohydrate consumed”.
STUDY DETAILS
8 participants cycled for 2h on three separate occasions to deplete muscle glycogen.
They consumed either 0, 1.5, or 3g glucose/kg body weight immediately after exercise and 2h later.
Blood glucose and insulin levels were measured before, during, and after exercise, along with muscle biopsies from the vastus lateralis.
Blood glucose and insulin increased significantly above pre-exercise levels in the 1.5g and 3g treatments during recovery but not in the 0g treatment.
Muscle glycogen storage rates were significantly higher in the carbohydrate treatments compared to the control but did not differ between the 1.5g and 3g treatments.
PRACTICAL TAKEAWAY
The results of this study show that to maximise muscle glycogen storage post-exercise, athletes should consume 1.5g of glucose per kg body weight. Increasing intake to 3g does not significantly improve storage rates, suggesting that moderate carbohydrate consumption is sufficient for optimal recovery within 4h. My recommendation for athletes is to prepare a post-exercise meal (or smoothie) with 25g protein and 1.5g/kg body weight of carbohydrates. This is not necessary after every session, but should definitely be used after high-intensity and long training sessions.
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DETRAINING: Physiological effects of tapering and detraining in world-class kayakers
During periods of reduced or stopped training, athletes often wonder how much fitness they are losing and how to reduce those loses. In this study, the authors set out to “provide insights into how different training reduction strategies affect key performance indicators in elite athletes”.
STUDY DETAILS
14 world-class kayakers were randomly split into two groups: reduced training (RT) (n=7) and training cessation (TC) (n=7).
The study measured 1-repetition maximum (1RM) strength, concentric velocity (V45%) in bench press and prone bench pull, and body composition at four time points: before and after tapering, and after RT or TC.
VO2 Max was measured on a kayak ergometer at three time points: pre-training, post-training, and post-intervention.
The TC group showed a greater decline in strength (-8.9% in bench press) compared to RT (-3.9%).
TC led to larger decreases in aerobic power (-11.3%) compared to RT (-5.6%), with both groups showing increases in skinfold measurements.
PRACTICAL TAKEAWAY
This study showed that there was no reduction in performance after a taper so athletes do not need to worry about losing fitness when tapering. Then, when comparing a total cessation of training with a minimised training routine over 5 weeks, the reduced training showed far less performance loss than training cessation. My recommendation is that athletes taking a post-season break should include some training during this period. In this study, one session of strength training and two endurance training sessions halved the loss in performance compared to total cessation.
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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 (465 studies and practical takeaways). Last week, the newsletter covered studies on the following topics:
Carbon monoxide supplementation to enhance altitude training
An integrated perspective of effort and perception of effort
How to equalize high- and low-intensity endurance exercise dose
Performance after accumulated work of differing intensities
Effects of magnesium supplementation on muscle soreness