RESEARCH: Studies reviewed this week: 20 December 2021 to 26 December 2021

STRENGTH: What Is the Optimal Strength Training Load to Improve Swimming Performance?

This study investigated low, medium and high strength training volume-loads for swimmers. The intervention was mid-season and lasted 3 months. The findings clearly showed the benefits of strength training, showing:

A large main effect of time for 1RM bench press: d = 1.38; 1RM leg extension: d = 1.55, and for 25 (d = 1.12), and 50 m (d = 1.97) front-crawl, similarly for start and turn performance.


No significant Group × Time interactions were shown in all strength swimming performances, start and turn tests.

This led the authors to conclude:

The addition of low training volume-loads as a regular part of a maximal strength training regime will elicit improvements in strength and swimming performance.

PRACTICAL TAKEAWAY - strength training is beneficial and it appears that a low training volume-load is sufficient (for swimmers).

HRV: Cardiac Parasympathetic and Anaerobic Performance Recovery After High-Intensity Exercise in Rowers

This study set out "to determine the effect of different high-intensity interval-training (IT) sessions on the postexercise recovery response and time course across varying recovery measure". This is an interesting area of research as it allows for scheduling and better allocating recovery periods depending on the training stimulus.

The authors found that:

Short-term responses to threshold, glycolytic, and VO2max IT in highly trained male and female rowers were similar.
Recovery time course was greatest following threshold compared with glycolytic and VO2max-focused training, suggesting a durational influence on recovery time course at HR intensities ≥80% HRmax.

PRACTICAL TAKEAWAY - threshold training appears to require the longest recovery period of all interval training types.

ALTITUDE: Similar Supine Heart Rate Variability Changes During 24-h Exposure to Normobaric vs. Hypobaric Hypoxia

This study investigated "the differences between normobaric (NH) and hypobaric hypoxia (HH) on supine heart rate variability (HRV) during a 24-h exposure". This is a useful way to understand the differences these two hypoxic conditions. The authors found that:

SpO2 was lower in both hypoxic conditions than in NN and was higher in NH than HH at H24. Subjects showed similarly higher HR during both hypoxic conditions than in NN.
No difference in HRV parameters was found between NH and HH at any time. The natural logarithm of root mean square of the successive differences (LnRMSSD) and the high frequency spectral power (HF), which reflect parasympathetic activity, decreased similarly in NH and HH when compared to NN.

The authors conclude:

Therefore, HRV can be analyzed similarly in NH and HH conditions.

PRACTICAL TAKEAWAY - HRV response to normobaric and hypobaric hypoxia is the same so HRV metrics can be used in the same way for either altitude camps or simulated altitude training like an altitude tent.

CHO: Impact of Dietary Carbohydrate Restriction versus Energy Restriction on Exogenous Carbohydrate Oxidation during Aerobic Exercise

This review discusses "the influence of low glycogen status resulting from carbohydrate restriction versus energy restriction on exogenous carbohydrate oxidation and examines the potential mechanism resulting in divergent responses in exogenous carbohydrate oxidation". The authors highlight that:

Results from this review indicate that rates of exogenous carbohydrate oxidation can be maintained when glycogen content is lower following carbohydrate restrictions, but may be reduced following energy restriction.
Exogenous carbohydrate may thus be an effective intervention to sustain performance following short-term energy adequate carbohydrate restriction, but may not be an effective ergogenic aid when glycogen stores are low due to energy restriction.

PRACTICAL TAKEAWAY - low glycogen stores can be mitigated through exogenous carbohydrate supplementation when following a lower-CHO diet but only if overall energy restriction is not happening.

CHO - Performance effects of periodized carbohydrate restriction in endurance trained athletes

This review investigated the train-low approach of periodized CHO restriction. The authors used followed strict inclusion criteria:

We conducted a meta-analysis of training studies that fulfilled the following criteria: a) inclusion of females and males demonstrating a VO2max ≥ 55 and 60 ml · kg− 1 · min− 1 , respectively; b) total intervention and training periods ≥ 1 week, c) use of interventions including training and/or recovery with periodized carbohydrate restriction at least three times per week, and d) measurements of endurance performance before and after the training period.

The results showed that:

The subsequent meta-analysis demonstrated no overall effect of CHO periodization on endurance performance compared to control endurance training with normal (high) CHO availability.
We therefore conclude that periodized CHO restriction does not per se enhance performance in endurance-trained athlete.

PRACTICAL TAKEAWAY - this review did not find benefits in research for a train-low approach.

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