RESEARCH: studies I shared this week: 11 to 17 July 2022

All of the studies I've shared (~500 studies) are available on the RESOURCES PAGE.

PROTEIN: Higher protein intake during caloric restriction improves diet quality and attenuates loss of lean body mass

This study set out "to examine how the change in self-selected protein intake during caloric restriction (CR) alters diet quality and lean body mass (LBM)". This is important to know as it helps us to understand what mechanisms are involved and therefore how to optimise for the desired outcomes. The authors found that:

Participants lost 5.0% of weight. Protein intake was 79g/d and 58g/d in the high protein (HP) and low protein (LP) groups, respectively, and there was an attenuated LBM (kilograms) loss in the HP compared with the LP group.
The increased Healthy Eating Index score in the HP compared with the LP group was attributed to greater total protein and green vegetable intake and reduced refined grain and added-sugar intake.

PRACTICAL TAKEAWAY - increasing dietary protein during CR improves diet quality and may be another reason for reduced LBM.

SUPPLEMENT: Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine

In this meta-analysis the authors set out to "quantify the proportion of the literature on caffeine supplementation that reports habitual caffeine consumption, and determine the influence of habitual consumption on the acute exercise response to caffeine supplementation". They found that:

A positive overall effect of caffeine was shown in comparison to placebo with no influence of relative habitual caffeine consumption.
Caffeine was effective for endurance, power, and strength exercise, with no influence of relative habitual caffeine consumption within exercise types.
Habitual caffeine consumption did not modify the ergogenic effect of caffeine in male, female, trained or untrained individuals.

PRACTICAL TAKEAWAY - a wash-out period is not necessary to receive the benefits of caffeine during sports performances.

PHYSIOLOGY: Decoupling of Internal and External Workload During a Marathon

This study investigated "the decoupling of internal-to-external workload in marathon running and investigated whether decoupling magnitude and onset could improve predictions of marathon performance". The internal metric was heart rate while the external metric was speed. The results were that:

The overall internal-to-external workload decoupling experienced was 1.16, first detected 25.2km into marathon running.
The low decoupling group (34.5% of runners) completed the marathon at a faster relative speed, had better marathon performance, and first experienced decoupling later in the marathon (33.4km) compared to those in the moderate, and high decoupling groups.
Marathon performance was associated with the magnitude and onset of decoupling, and when included in marathon performance models utilising CS and the curvature constant, prediction error was reduced from 6.45 to 5.16%.

PRACTICAL TAKEAWAY - durability and the ability to prevent the onset of decoupling will result in better marathon performances.

INTERVALS: Bout duration in high-intensity interval exercise modifies hematologic, metabolic and antioxidant responses

In this study the authors "compared hematologic, metabolic and antioxidant responses between three high-intensity interval exercise (HIIE) trials of different bout duration and a continuous exercise trial (CON), all with equal average intensity, total work, and duration". The value of this research is that it can help us to understand how best to structure interval training.

The different exercise modalities were "four trials involving 20 min of cycling, either continuously (49% of power at VO2max, PPO), or intermittently with 48 10-s bouts (HIIE10), 16 30-s bouts (HIIE30) or 8 60-s bouts (HIIE60) at 100% PPO, with a 1:1.5 work-to-recovery ratio at 15% PPO". The authors found that:

Post-exercise leukocyte count, uric acid concentration, glucose concentration, and plasma volume change were greater in HIIE60 compared to all other trials.
Urine lactate concentration 1 h post-exercise increased compared to pre-exercise only in HIIE60, and this was related with the higher blood lactate concentration during exercise in that trial.
Shorter bouts of HIIE (30 s or 10 s) induce lower blood cell perturbations, metabolic stress, and antioxidant responses compared to the commonly used 1-min bouts.

PRACTICAL TAKEAWAY - intervals of 60" are a superior stimulus for adaptation than shorter (30" or 10") intervals.

CHO: High Energetic Demand of Elite Rowing - Implications for Training and Nutrition

In this paper the authors aimed to study "exercise energy expenditure (EEE) and intensity related substrate utilization (SU) of elite rowers during rowing (EEEROW) and other (EEENON-ROW) training". The data came from 14 elite open-class male rowers. The results showed that:

EEEROW for zone 1 to 3 ranged from 15.6 kcal·min-1 to 49.8 kcal·min-1, with carbohydrate utilization contributing from 46.4% to 100.0%.
During a high-volume, a high-intensity, or a taper week, total energy requirement (TER) was estimated to 6,775 kcal·day-1, 5,772 kcal·day-1, or 4,626 kcal∙day-1.
EEE in elite open-class male rowers is remarkably high already during zone 1 training and carbohydrates are dominantly utilized, indicating relatively high metabolic stress even during low intensity rowing training.

PRACTICAL TAKEAWAY - energy requirements for elite athletes are high and even easy days require significant carbohydrate.

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