RESEARCH: studies shared from 6 to 12 Mar 23

All the studies I've shared are available on the RESOURCES PAGE.

This week's quick summary:

• Variations of workload prior to injury
• Dose-response of protein on muscle protein synthesis
• Addressing confusion in training periodisation
• A new metric for hypoxic dose
• Training and health differences between ultramarathons and shorter distances

INJURY: Variations of workload indices prior to injuries: A study in trail runners

STUDY DETAILS

1. Twenty-five trail runners were monitored daily for 52 weeks using global positioning systems (GPSs) to determine the total distance covered.
2. Additionally, a rate of perceived exertion (RPE) scale was applied to determine session-RPE (sRPE: RPE multiplied by training time).
3. The accumulated load (AL), acute: chronic workload ratio (ACWR), training monotony (TM), and training strain (TS) indices were calculated weekly for each runner.
4. There were significant weekly increases in acute load, acute: chronic workload ratio, training monotony, and training strain for sRPE, total distance, and training time in the weeks prior to an injury’s occurrence.
5. The main finding of the present study is that in the three weeks before an injury occurred, sudden weekly changes occurred in acute loads for sRPE, training time, and total distance.
6. These results suggest that athletes and coaches should pay special attention to the periodization of training and the monitoring of workloads, avoiding high monotony, and allowing changes in loads that induce adaptation to the stimulus.

PRACTICAL TAKEAWAY

Acute increases in training load were likely to increase injury occurrence. To limit the likelihood of injury, athletes first need to be monitoring their training load (keep a detailed training log) and then managing any increase in training load carefully. I recommend thinking about long-term development and continuing to be cautious even when training is going very well. In this study it appeared that increases in training load of greater than 10-15% were most likely to result in injury so that can be a good guideline for managing increases in load.

PROTEIN: Dose-response effects of dietary protein on muscle protein synthesis during recovery from endurance exercise in young men

Previous studies I've shared have shown that protein can increase adaptation to endurance training and that 20-40g of pre-sleep protein stimulates whole body protein synthesis after resistance training. This study investigated whether or not "protein ingestion increases skeletal muscle protein synthesis rates during recovery from endurance exercise".

STUDY DETAILS

1. We aimed to determine the effect of graded doses of dietary protein co-ingested with carbohydrate on whole-body protein metabolism, and skeletal muscle myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis rates during recovery from endurance exercise.
2. 48 healthy, young, endurance-trained men...ingested 45g carbohydrate with either 0 (0g PRO), 15 (15g PRO), 30 (30g PRO), or 45 (45g PRO) g intrinsically l-[1-13C]-phenylalanine and l-[1-13C]-leucine labeled milk protein after endurance exercise.
3. Protein intake resulted in ∼70%-74% of the ingested protein-derived phenylalanine appearing in the circulation.
4. Whole-body net protein balance increased dose-dependently after ingestion of 0, 15, 30, or 45g protein.
5. 30g PRO stimulated a ∼46% increase in MyoPS rates (%/h) compared with 0g PRO and was sufficient to maximize MyoPS rates after endurance exercise.
6. Ingestion of 30g protein is sufficient to maximize MyoPS rates during recovery from a single bout of endurance exercise.

PRACTICAL TAKEAWAY

To stimulate skeletal muscle protein synthesis post-exercise, a 30g dose of protein is sufficient. The effect of protein is dose dependent so it's important to check the quantity of protein being ingested when using a protein drink or bar for recovery (a single serving can be anywhere from 15 to 45g depending on the product). While it's not clear that the post-exercise "window" for ingesting protein for recovery is critical, in this study the participants did ingest the protein immediately after exercise.

PERIODISATION: Addressing the confusion within periodization research

I have shared a range of studies on periodisation that look at different models and approaches to planning training (search for "periodisation" on my resources page). In this editorial, the authors express their concern about "many review and opinion papers on periodization in which we feel the questioning is far too simplistic and misses the breadth and robustness of the historical development of periodization". Here are some highlights and interesting points from the paper.

STUDY DETAILS

1. The historical development of periodization has a long and rich history dating back several centuries.
2. Recently, there has been an increased push to use a training strategy that is more in-the-moment-focused. Instead of a long-term, detailed training prescription, this approach to training involves a format in which training is dictated by an athlete’s alleged current state (e.g., readiness, and fatigue, which are often subjective), and to a large degree, based on a certain selection format, assembled session to session.
3. These training models are not periodization models and are actually programming models, this is because these flexible training models are driven by day-to-day and week-to-week programming decisions, often based on athletes’ subjective feelings and not objective evidence or an over-arching periodization strategy.
4. Periodization is a conceptual outline dealing with timelines and fitness phases; depending upon the goal of the training process, it creates time-direction of training volume, intensity, and task specificity factors
5. An appreciation of the differences in training advanced and elite-level competitors with long training histories compared to the very forgiving population of untrained or novice individuals, who readily respond to almost any training stimulus, is essential for making sense of the available data.
6. Recognizing and developing all facets of successful performance is critical to achieve the desired consistent and long-term results, whether it is on the athletic field or in any occupation requiring high levels of performance.

PRACTICAL TAKEAWAY

The history and effectiveness of training periodisation shows that it is an important part of long-term athlete development. It is important to remember this when hearing criticisms of using periodisation and not to dismiss it as a valid means of planning training. I recommend starting each season with a carefully constructed season plan that builds in different periods of training focus depending on the athlete's objectives and development needs.

ALTITUDE: Time for a new metric for hypoxic dose?

Most of the guidance on altitude training recommends 3 to 4 weeks of training at 2000 to 2500m of altitude. In this paper the authors "propose a model where hypoxic dose is termed “kilometer hours” and defined as km·h = (m/1,000) × h, where m indicates elevation of exposure in meters and h indicates total duration of exposure in hours".

STUDY DETAILS

1. Specifically, we sought individual, deidentified raw data from all altitude studies reporting Hbmass measured via CO rebreathing pre and post altitude.
2. Data from 27 studies were available for analysis, and many contained serial measurements obtained during periods of exposure, allowing for multiple estimates of the change in Hbmass over time.
3. For each of the studies, estimates of the effect of altitude, both during and up to 2 days post altitude, were obtained using linear mixed models applied to log transformed Hbmass values, with “subject” as a random effect and allowing for possible autocorrelation within subjects.
4. Whereas the linear model was a reasonable fit to the data over most of the range of kilometers hour values, the quadratic model did provide a significantly better fit, over the full range of kilometer hour values available, whereas there was little difference between the quadratic and exponential models.
5. There are a multiplicity of ways in which to accumulate kilometer hours. For example, 19 days continuously at 2,760 m resulted in 1,258 km·h; similarly 9 h/day exposure to 2,860 m for 48 days generated 1,236 km·h.
6. Thus, lower altitudes must be balanced by longer exposures to provide sufficient stimulus for adaptation.

PRACTICAL TAKEAWAY

Training at altitude is an effective means of improving performance so it is important to be able to measure it effectively. While a trip to a single location for altitude training is possible, this type of measurement allows for multiple different altitude and durations to be compared and measured effectively. I recommend using kilometer hours as a useful metric for measuring altitude exposure.

When I shared this research as a tweet, there was some good discussion suggesting that the magnitude of the stimulus based on SpO2 rather than just the altitude dose should be considered. I agree with this idea and will be investigating it further.

TRAINING: Differences in training and health characteristics between trail ultrarunners and shorter distance runners

"The primary aim of the study was to compare select training and health characteristics between ultramarathon and shorter distance runners participating in a trail race series."

STUDY DETAILS

1. A questionnaire was sent to all participants who signed up for a trail race series, including distances of 10 km, half marathon, 50 km, 80.5 km (50 mi), and 100 km.
2. There were 59 participants (27 ultramarathoners and 32 half marathon/10-km runners) who completed the questionnaire.
3. There were no significant differences in reported history of stress fracture or sleep quality scores between the ultramarathon and half marathon/10-km groups.
4. Over half of both groups reported trying to change body weight to improve performance, without significant differences between groups.
5. A significantly greater proportion of the ultramarathoners reported an episode of binge eating in the 4 wk preceding the race.
6. Despite differences in training volume, we did not find different injury, sleep, and nutrition data between the ultramarathoners and half marathon/10-km runners, with the exception of more ultramarathoners reporting binging behaviors in the 4 wk leading up to the race.

PRACTICAL TAKEAWAY

The increased training volume of ultramarathon runners does not appear to present an injury risk or a negative impact on sleep. However, the higher energy demands need to be carefully considered as it appears that the ultramarathon runners may have been under-fuelling their training leading to episodes of binge eating in the month before the race. It is important to "fuel the work" required and ultramarathon runners have a higher energy demand and need for thorough fuelling and nutrition practices.