RESEARCH: Studies reviewed this week: 26 April 2021 to 02 May 2021

LOAD: Determinants of the diurnal course of salivary alpha-amylase

This study looked into a biomarker that I've never thought about before: salivary alpha-amylase. The authors explain that it may be a marker for adrenergic activity and they investigated "the diurnal pattern of salivary amylase and its determinants".

The results showed that:

Salivary alpha-amylase activity shows a distinct diurnal profile pattern with a pronounced decrease within 60 min after awakening and a steady increase of activity during the course of the day.
Mixed models showed a relative independence of diurnal salivary alpha-amylase from momentary stress and other factors, but significant associations with chronic stress and mood.

PRACTICAL TAKEAWAY - salivary-amylase may prove a useful marker to predict sympathetic activity and therefore could be a complement to HRV measurement.

COVID: The Impact of Coronavirus (COVID-19) Related Public-Health Measures on Training Behaviours of Individuals Previously Participating in Resistance Training

I shared a previous study that showed during the pandemic runners were running more, but less workouts and with less motivation. In this study the authors set out to investigate "the impact of lockdown upon resistance training (RT), and how people adapted their RT behaviours".

The authors found that:

  • A majority of individuals (82.8%) maintained participation in RT during-lockdown.
  • There was reduced probability of training in privately owned gyms (~ 59% to ~ 7%) and increased probability of training at home (~ 18% to ~ 89%).
  • Greater probability of training using a full-body routine (~ 38% to ~ 51%).
  • Reduced probability of resistance machines (~ 66% to ~ 13%) and free weight use (~ 96% to ~ 81%), and increased probability of bodyweight training (~ 62% to ~ 82%).
  • Moderate reduction in the perception of effort experienced during-training.

PRACTICAL TAKEAWAY - people who engaged in resistance training adapted their training to make use of the facilities available to them, however, the pandemic had a distinct impact on the motivation and quality of their workouts (similar to the running observations).

STRENGTH: Maximal isometric strength indices are associated with the oxygen cost of walking and running in recreationally active men and women

Strength training is important useful for athletes (you can find a range of papers supporting it here). In this study the authors set out to assess the "associations of maximal isometric strength and movement economy".

The authors tested oxygen consumption and maximal isometric leg extensor, leg flexor and handgrip strength to determine the relationship between strength and economy. The results showed that:

The oxygen cost differed statistically for the majority of velocities when participants were split by the median of leg extensor strength and the average of all strength variables.
Our data underline the importance of maintaining maximal strength in order to perform activities with low to moderate oxygen demands.

PRACTICAL TAKEAWAY - strength training is important as it can contribute to greater economy at low speeds.

LOAD: The role of perfectionism in predicting athlete burnout, training distress, and sports performance

This study set out to examine "the influence of perfectionistic strivings and perfectionistic concerns on athlete burnout and two key indicators of overtraining syndrome". This is a fascinating area to explore because it considers a factor that is not traditionally incorporated into load models or even mood models.

The authors found that:

Perfectionism was a significant predictor of athlete burnout and both indicators of overtraining (training distress and subjectively perceived sports performance).
When the one-year longitudinal relationships were regarded, only perfectionistic strivings significantly predicted decrease in burnout, and, for sports performance, the predictive power of both dimensions of perfectionism was even more pronounced.

PRACTICAL TAKEAWAY - mental load and stress (in this case perfectionist tendencies) have a significant impact on long-term development and performance and deserve attention in addition to traditional training load.

PROTEIN: Protein Source and Quality for Skeletal Muscle Anabolism in Young and Older Adults

Protein intake plays a vital role in strength development and maintenance of muscle mass. However, this is the first study I've seen that considers the quality of the protein source. The authors set out "to determine the effect of protein source/quality on acute muscle protein synthesis (MPS) and changes in lean body mass (LBM) and strength, when combined with resistance exercise (RE)".

The results of the systematic review showed that:

Analysis revealed an effect favoring higher-quality protein for postprandial MPS at rest and following RE in young and older adults.
The current review suggests that protein quality may provide a small but significant impact on indices of muscle protein anabolism in young and older adults.

PRACTICAL TAKEAWAY - when possible, make sure to use the highest possible quality source of protein that you can.

CHO: Carbohydrate feeding and glycogen synthesis during exercise in man

This is an older study which provides some insight into how the body uses CHO when it is ingested during exercise.

The highlights from the paper were that:

During exercise glycogen repletion was restricted to type IIA and IIB fibers, whereas during rest glycogen synthesis occurred both in type I and type II fibers.
Oral carbohydrate administered during exercise may not only provide substrate for energy metabolism, but can also be utilized for glycogen synthesis in the non-active muscle fibers.

PRACTICAL TAKEAWAY - ingesting CHO during exercise plays multiple roles and is important especially when performing multiple training sessions a day or during high training load periods.

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