NUTRITION: Caffeine Exacerbates Hyperventilation and Reductions in Cerebral Blood Flow in Physically Fit Males Exercising in the Heat
I have shared multiple studies on caffeine which are all positive (caffeine aids performance, caffeine functions for difference genotypes, caffeine aids neuromuscular function). However, are there any cases in which caffeine is not beneficial? This study set out ti investigate "whether caffeine affects hyperthermia-induced hyperventilation or reductions in the cerebral blood flow index". The authors found that:
A moderate dose of caffeine [5mg/kg] exacerbates hyperthermia-induced hyperventilation and reductions in the cerebral blood flow index during exercise in the heat [37C] with severe hyperthermia.
PRACTICAL TAKE AWAY - caffeine is a useful ergogenic aid, but it may be worth testing and being cautious when using caffeine in very hot environments.
Low iron can be a problem for endurance athletes and especially runners due to hemolysis from the pounding of the running stride. Of course if this is a concern for you then it is important to get the advice from a doctor. However, it is useful to read the research on optimal treatment strategies to understand what course of action may be optimal. The authors of this review found that it is optimal to follow:
A contemporary strategy of oral iron therapy entailing morning supplementation, ideally within the 30min following morning exercise, and in athletes experiencing gut sensitivity, consumed on alternate days or at lower doses.
PRACTICAL TAKE AWAY - if you need to supplement iron it's best to take it in the morning and after exercise.
TRAINING: Effects of six-week sprint interval or endurance training on calculated power in maximal lactate steady state
This is a particularly interesting study because it teases out some of the details of the impacts of different training types. "The purpose of the study was to evaluate and compare the influence of sprint interval training (SIT) and endurance training (ET) on calculated power in maximal lactate steady state (PMLSS)".
The SIT group did 3 sessions a week of 30" sprint / 4.5' recovery repeated 4 to 6 times. The ET group did 3 sessions a week of 60' at a sub-threshold intensity. The study lasted for 6 weeks. The authors found that:
While SIT primarily affects ⩒Lamax, ET has an increasing effect on ⩒O2max. It appears that both types of training significantly improved the calculated PMLSS by differently influencing ⩒Lamax and ⩒O2max.
PRACTICAL TAKE AWAY - while it is possible to improve PMLSS through different training, it is important to identify which physical qualities are required to match the demands of the race to ensure the best training plan is used.
NUTRITION: Acute effects of caffeine supplementation on resistance exercise, jumping, and Wingate performance: no influence of habitual caffeine intake
In the first study I shared above I included multiple links to caffeine studies that showed the benefit for performance. This study "explored the influence of habitual caffeine intake on the acute effects of caffeine ingestion on resistance exercise, jumping, and Wingate performance". The subjects were divided into low caffeine users and moderate-to-high caffeine users and were tested with either a placebo of 3mg/kg caffeine acute dose.
The authors found that:
Habitual caffeine intake might not moderate the ergogenic effects of acute caffeine supplementation on resistance exercise, jumping, and Wingate performance.
PRACTICAL TAKE AWAY - it's ok to drink coffee in race week as you will still get the desired acute affects of in-race caffeine ingestion.
This study provides some useful CHO intake guidelines for athletes exercising for more than 90':
- Athletes should ingest carbohydrate during endurance exercise even if they have ‘carbohydrate-loaded’ before exercise.
- Athletes should probably consume 100 ml every 10 min of a dilute (3-5g/100 ml) carbohydrate solution during the first hour; and
- thereafter increase the carbohydrate concentration to ∼10g/100ml to match the peak rates of plasma glucose oxidation.
PRACTICAL TAKE AWAY - CHO ingestion is beneficial to performance and the rates of ingestion should be carefully considered depending on the starting state of the athlete.
A useful review highlighting the benefits of creatine supplementation. Key points from this review:
Of the approximately 300 studies that have evaluated the potential ergogenic value of creatine supplementation, about 70% of these studies report statistically significant results.
No study reports a statistically significant ergolytic effect.
Short-term creatine supplementation has been reported to improve maximal power/strength (5-15%), work performed during sets of maximal effort muscle contractions (5-15%), single-effort sprint performance (1-5%), and work performed during repetitive sprint performance (5-15%).
Although not all studies report significant results, the preponderance of scientific evidence indicates that creatine supplementation appears to be a generally effective nutritional ergogenic aid for a variety of exercise tasks in a number of athletic and clinical populations.
PRACTICAL TAKE AWAY - creatine is an effective supplement for power/strength, sprint, and repetitive sprint performance.