RESEARCH: Studies reviewed this week: 21 June 2021 to 27 June 2021

STRENGTH: Aerobic exercise intensity does not afect the anabolic signaling following resistance exercise in endurance athletes

Interference between strength and endurance training is important to consider in planning and periodising training protocols. This study looked into the details to determine "whether intensity of endurance stimulus within a concurrent training paradigm infuenced the phosphorylation of signaling proteins associated with the mTOR and AMPK networks". The study used cyclists and training sessions and a range of sessions from resistance training of 6x8 squats at 80% 1-RM to endurance training sessions such as 6x3' at 85% VO2 Max.

The resutls showed that:

These data do not support a molecular interference efect in cyclists under controlled conditions.
There was no intensitydependent regulation of AMPK, nor diferential activation of anabolism with the manipulation of endurance exercise intensity.
These data suggest that endurance athletes need not be concerned with the intensity of their endurance session (moderate vs. high intensity) afecting their strength adaptation, when the two exercise modes are performed in close proximity to one another.

PRACTICAL TAKEAWAY - don't worry too much about strength or endurance sessions interferring with each other. This provides a bit more flexibility to make sure that you fit in both types of training.

TRAINING: The Aerobic and Anaerobic Contribution During Repeated 30-s Sprints in Elite Cyclists

This study is particularly useful as it's design intends to help coaches and athletes understand the impact of including short sprints in low-intensity training (LIT). In particular, the authors explain the that they:

Used the gross efficiency (GE)-method to investigate: (1) the absolute and relative aerobic and anaerobic contributions during 3 × 30-s sprints included each hour during a 3-h low-intensity training (LIT)-session by 12 cyclists, and (2) how the energetic contribution during 4 × 30-s sprints is affected by a 14-d high-volume training camp with (SPR, n = 9) or without (CON, n = 9) inclusion of sprints in LIT-sessions.

The results showed that:

Moderate decreases in power within sets of repeated 30-s sprints are primarily due to a decrease in anaerobic power and to a lesser extent in aerobic power.
The repeated sprint-ability (multiple sets) and corresponding energetic contribution are maintained during prolonged cycling in elite cyclists.

This led the authors to conclude that:

Including a small number of sprints in LIT-sessions during a 14-d training camp improves sprint-ability mainly through improved anaerobic power.

PRACTICAL TAKEAWAY - make sure to maintain some sprints or strides in your low intensity training blocks to maintain or develop your anaerobic power.

RACING: Sex Differences in Neuromuscular Fatigue and Changes in Cost of Running after Mountain Trail Races of Various Distances

Female athletes have been shown to experience less neuromuscular fatigue than male athletes during ultramarathon races. In this study the authors wanted to extend the research to understand if this has an impact on shorter trail races and on running economy. In particular they set out to "characterize sex differences in fatigability over a range of running distances and to examine possible differences in the post-race alteration of the cost of running (Cr)".

The results showed that:

Compared to males, females displayed a smaller decrease in maximal strength in knee extensors, independent of race distance.
In shorter races only, females displayed less peripheral fatigue in plantar flexors compared to males.
Cost of running increased similarly in males and females.

PRACTICAL TAKEAWAY - I'm not sure there is much that we can do with this information, but it is interesting to be aware of the differences between male and female runners.

NUTRITION: Carbohydrate does not augment exercise-induced protein accretion versus protein alone

I've shared plenty of studies about protein and recovery (see the resources page) so we know that protein is important. However, a useful additional question to ask is whether this protein should be consumed by itself or with other nutrients. In this study set out to test the hypothesis that "CHO and protein coingestion would augment muscle protein synthesis (MPS) and inhibit muscle protein breakdown (MPB) at rest and after resistance exercise".

The results showed that:

Exercise increased MPS and MPB, but there were no differences between PRO and PRO+CARB in the rested or exercised legs.
The concurrent ingestion of 50 g of CHO with 25 g of protein did not stimulate mixed MPS or inhibit MPB more than 25 g of protein alone either at rest or after resistance exercise.

PRACTICAL TAKEAWAY - for the purposes of muscle protein synthesis it is not necessary to consume CHO with your PRO for recovery. [It is worth considering the need for glycogen replenishment after hard training which is a different reason for including CHO in your recovery meal / shake.]

HEAT: Training wearing thermal clothing and training in hot ambient conditions are equally effective methods of heat acclimation

Preparing for hot racing conditions is hard. There's a lot of work investigating hot-water immersion, heat camps, sauna protocols, etc (see resources page). All of this research means it can be confusing to decide what to do for your heat preparation. This study set out to compare three different protocols:

1) 50-min cycling per day in 35 °C, 2) 50-min cycling per day wearing thermal clothing, and 3) 50-min cycling wearing thermal clothing plus 25 min hot water immersion per day.

The results showed that:

There were no significant between-group differences in any of the determined variables.
At termination of the 30-min all-out test, the increase in blood lactate concentration, rate of perceived exertion and sweat rate were not different between the three interventions.
Daily training sessions conducted either in ambient 35 °C, while wearing thermal clothing in temperate conditions or while wearing thermal clothing combined with hot water immersion are equally effective for improving exercise performance in the heat.

PRACTICAL TAKEAWAY - choose the heat protocol that is easiest for you. I would suggest that for practical reasons it is most likely that athletes have access to thermal clothing and this would be an easier option than finding a heat chamber and as the addition of hot-water immersion did not provide any additional benefits it's not necessary to go through that discomfort.

HRV: Effects of varying training load on heart rate variability and running performance among an Olympic rugby sevens team

In this study the authors set out "to evaluate weekly heart rate variability (HRV) responses to varying training load among an Olympic rugby sevens team and to assess whether HRV responses informed on training adaptation". In a retrospective study they analyzed three weeks of data including HRV and training load.

The authors concluded that:

In week 3, players accomplished greater external training loads with minimal impact on internal load while wellness was preserved.
Players demonstrated less fluctuations in LnRMSSD, interpreted as an improved ability to maintain cardiac-autonomic homeostasis despite increments in training load.
Monitoring the magnitude of daily fluctuations in LnRMSSD in response to varying training loads may aid in the evaluation of training adaptations among elite rugby players.

PRACTICAL TAKEAWAY - if you are able to increase your training load while your HRV stays constant that is a good indication that you are able to handle the added load.

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