RESEARCH: studies reviewed this week - 12 October 2020 to 18 October 2020

NUTRITION: High-Fat Ketogenic Diets and Physical Performance: A Systematic Review

There have been a number of studies on diets including a ketogenic diet (this study showed an impact on bone health following a ketogenic diet). This systematic review aimed "to assess the effect of ketogenic diets on physical performance compared with mixed macronutrient diets". The authors found that:

Overall, the majority of null results across studies suggest that a [ketogenic diet] does not have a positive or negative impact on physical performance compared with a [control] diet.

PRACTICAL TAKE AWAY - it is still uncertain which diet is optimal for performance and it seems that many options can work for different athletes. It would seem that if you have reasons to follow a ketogenic diet (other than performance) there may be limited impact on performance if you do choose this diet.

NUTRITION: Current hydration guidelines are erroneous: dehydration does not impair exercise performance in the heat

There are some studies which suggest losing as little as 2% in weight due to dehydration may impact performance. This study set out to test this in a blinded and in a real world environment. The aim of the study was to "investigate the effect of blinded hydration status on cycling time-trial performance in the heat with ecologically valid facing wind speed conditions". The authors found:

When well-trained cyclists performed a 25 km cycling time trial under ecologically valid conditions and were blinded to their hydration status, performance, physiological and perceptual variables were not different between trials.

PRACTICAL TAKE AWAY - some dehydration (up to 3% tested in this study) does not affect performance.

TRAINING: Downhill Running: What Are The Effects and How Can We Adapt?

I have shared a couple of resources on downhill running in the past: this study showed that changing footstrike pattern did not reduce forces and this study showed that ground impact forces increased 54% for a -9% incline. This narrative review ivestigated the research available on downhill running. Of significance, the authors found that:

There is growing evidence to suggest that preventive strategies that consist of prior exposure to DR are the most effective to better tolerate DR.

The effectiveness of in-situ strategies such as lower limb compression garments and specific footwear remains to be confirmed.

PRACTICAL TAKE AWAY - prepare for running in a downhill race by replicating the descents in your training.

TRAINING: The Training Characteristics of the World's Most Successful Female Cross-Country Skier

I refer to this study every year when I'm thinking about training and planning for the next year. It's a beautiful study that provides data and perspective on training planning and periodisation for a supurb athlete. Including in the study are:

  • Longitudinal Training Characteristics
  • Training Characteristics of the Five Most Successful Seasons
  • Exercise Modes
  • Altitude Training
  • Tapering toward International Championships
  • Annual Periodization of Training

PRACTICAL TAKE AWAY - I highly recommend reading this study in depth.

TRAINING: High-intensity decreasing interval training (HIDIT) increases time above 90% VO2peak

In this previous study I shared the take-away that a fast start to VO2Max intervals could induce greater training benefits. This study looks into a slight variation of HIIT intervals by decreasing the duration of each interval. The HIDIT protocol used was a series of intervals following this format:

  1. 3' hard / 2' easy
  2. 2' hard / 80" easy
  3. 1' hard / 40" easy
  4. 45" hard / 30" easy
  5. 30" hard / 20" easy
  6. repeat step 5 until volitional exhaustion.

The authors found that:

In light of the favorable or similar physiological and/or perceptual responses to HIDIT compared to the other protocols and given the improved capability to prolong the time close to V˙O2peak, it could be used as a preferable method to elicit similar or greater physiological adaptations.

PRACTICAL TAKE AWAY - HIDIT intervals are a good option to maximise the benefit from VO2Max training.

EQUIPMENT: An Assessment of Running Power as a Training Metric for Elite and Recreational Runners

I have tried the Stryd power meter for running and I found the data quite interesting, however, in the end I felt like I was just collecting another data point without actually adjusting or altering my training in any way. This study "sought to investigate a novel training tool, the Stryd Running Power Meter, and the applicability of running power (and its individually calculated run mechanics) to be a useful surrogate of metabolic demand (V̇o2), across different running surfaces, within different caliber runners". The authors found that:

A weak but significant relationship was found between running power and V̇o2 considering all participants as a homogenous group (r = 0.29); however, when assessing each population individually, no significant relationship was found.

Although metabolic demand differed significantly between surfaces at most speeds, run power did not accurately reflect differences in metabolic cost between the 2 surfaces.

Running power, calculated via the Stryd Power Meter, is not sufficiently accurate as a surrogate of metabolic demand, particularly in the elite population.

PRACTICAL TAKE AWAY - running power is an interesting concept, but the current devices are not reflective of metabolic demand and for trail runners the power measurements do not reflect the differences in running surface.

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