RESEARCH: Studies reviewed this week: 12 April 2021 to 18 April 2021

NUTRITION: Increased Cardiorespiratory Stress During Submaximal Cycling After Ketone Monoester Ingestion in Endurance-Trained Adults

I've shared a few studies on ketones before and they all showed that ketone ingestion did not enhance performance. In this study the authors set out to use a thorough protocol and to establish the results based on carefully considered training status of the participants. The protocol they used was:

Using a randomized, double-blind, counterbalanced design, we examined the effect of ingesting a ketone monoester (KE) supplement (600 mg/kg body mass) or flavour-matched placebo in endurance-trained adults (n=10 males, n=9 females; VO2peak=57±8 ml/kg/min).

The results were that:

KE versus placebo ingestion increased plasma [β-hydroxybutyrate] before exercise, ventilation and heart rate during exercise, and rating of perceived exertion at the end of exercise. Plasma [β-hydroxybutyrate] remained higher after KE vs placebo ingestion before the time-trial, but performance was not different.

Leading the authors to conclude:

Acute ingestion of a relatively large KE bolus dose increased markers of cardiorespiratory stress during submaximal exercise in endurance-trained participants.

PRACTICAL TAKEAWAY - ketone ingestion does not apear to enhance performance.

TRAINING: Time Spent Near VO2max During Different Cycling Self-Paced Interval Training Protocols

I like practical studies that seek to answer questions I've had about how I presribe training. The authors of this study set out to compare the time spent near VO2max during 4 different self-paced interval training sessions. The different self-paced sessions were:

Comprised 4 repetitions of 4 minutes of cycling with 1 minute (4/1) or 2 minutes (4/2) of active recovery or 8 minutes of cycling with 2 minutes (8/2) or 4 minutes (8/4) of active recovery.

The results were that:

  • The 8/4 session provided higher absolute tVO2max and t95VO2max than 8/2 and 4/1.
  • The 4/2 protocol elicited higher relative tVO2max and t95VO2max than 4/1 and 8/2.
  • Session 4/2 elicited greater mean power output than 4/1, and 8/2.

PRACTICAL TAKEAWAY - intervals should comprise 2:1 work:rest ratios to prioritize time at VO2Max.

TRAINING: The Inclusion of Sprints in Low-Intensity Sessions During the Transition Period of Elite Cyclists Improves Endurance Performance 6 Weeks Into the Subsequent Preparatory Period

A previous study I shared showed that including sprint intervals during long rides did not negatively impact the low-intensity training stimulus. This study set out to investigate adding "including repeated sprints in a weekly low-intensity (LIT) session during a 3-week transition period on cycling performance 6 weeks into the subsequent preparatory period (PREP) in elite cyclists".

The cyclists "included 3 sets of 3 × 30-second maximal sprints in a weekly LIT session during a 3-week transition period". The results showed that:

Including sprints in a weekly LIT session during the transition period of elite cyclists provided a performance advantage 6 weeks into the subsequent PREP, which coincided with a higher performance VO2.

PRACTICAL TAKEAWAY - including sprints (or strides) during low-intensity training can be a useful method to transition to a specific training block.

TRAINING: Do We Need a Cool-Down After Exercise?

This narrative review provides a thorough review of cool-downs after exercise. The authors conclude:

Most evidence indicates that active cool-downs do not significantly reduce muscle soreness, or improve the recovery of indirect markers of muscle damage, neuromuscular contractile properties, musculotendinous stiffness, range of motion, systemic hormonal concentrations, or measures of psychological recovery. It can also interfere with muscle glycogen resynthesis.

PRACTICAL TAKEAWAY - a cool-down may not be necessary or beneficial after your training.

TRAINING: Is Rating of Perceived Exertion a Valuable Tool for Monitoring Exercise Intensity During Steady-State Conditions in Elite Endurance Athletes?

RPE is a fantastic means of measuring effort and training load. It's free and accessible to everyone and it doesn't require batteries or devices to measure it. However, in some ways even RPE needs to be "calibrated". The authors "investigated between-subject variation and effect of exercise mode and sex on Borg RPE (6–20) in relation to heart rate (HR), oxygen uptake (VO2), and capillary blood lactate concentrations".

The findings were that:

A strong relationship was found between RPE and %HR, %VO2, and capillary blood lactate concentrations. The between-subject coefficient of variation (SD/mean) for %HR and %VO2 decreased linearly with increased RPE.
Compared with cycling, running induced a systematically higher %HR and %VO2 with these differences being greater at lower intensities.

PRACTICAL TAKEAWAY - runners may need additional means than RPE to measure low-intensity efforts to ensure that they are running easy enough.

TRAINING: The effects of training with high‐speed interval running on muscle performance are modulated by slope

Does it matter what gradient you run your intervals on? The authors "examined changes in selected muscle performance parameters after 8 weeks of interval training using two opposite running inclinations. We hypothesized that the uphill training will affect endurance muscle performance outcomes, whereas the downhill training will affect power muscle performance outcomes".

The key findings were that:

Downhill high‐speed interval running resulted in an augmented rate of force development.
Uphill high‐speed interval running improved resistance to fatigue.

PRACTICAL TAKEAWAY - consider the type of terrain you run on depending on the training adaptation you are trying to achieve.

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