RED-S and Winter Training: Essential Guidelines for Endurance Athletes

Winter training presents unique risks for endurance cyclists and runners when it comes to maintaining adequate energy availability. Understanding and preventing Relative Energy Deficiency in Sport (RED-S) is important throughout the year, but here are some things to watch out for specifically during these colder months when energy demands can change

Understanding RED-S in the Winter Context

Relative Energy Deficiency in Sport occurs when an athlete's energy intake doesn't meet the demands of their training, leading to impaired physiological function.

During winter, several factors can increase the risk of RED-S:

1. Lower training volumes

Athletes who are sensitive about their weight can often over compensate in winter months to the lower volume of training. If you are not sure what you should be eating during a lighter base period of training then you can track calories and energy expenditure using tools like MyFitnessPal and Cronometer or use the Athlete’s Plate system.

2. Higher intensity

• It can be easy to dismiss the load of more intense workouts because they are shorter and often score less on Training Stress in various training apps, which tend to be a bit time weighted. This is particularly true if you are measuring based on heart rate.
• To make strength gains with heavy weight training, which is often the focus of endurance athletes in the winter months, you need to be adequately fuelled both before and after  workouts.

3. Holiday-related stress and irregular eating patterns

• This can lead to athletes trying to ‘over-compensate’ or coming into workouts too fasted because they know they will be eating a lot later. For those with a history of disordered eating, this period can lead to risky behaviours around binge eating and purging.
• Holiday food is often not ideal for recovery or for workout preparation, being rich, hard to digest and heavy in carbohydrates. Sticking to you usual pre and post training snacks and eating a moderate amount of holiday food can be a better solution.

Evidence-Based Prevention Strategies

1. Energy Availability Monitoring

Research published in the International Journal of Sport Nutrition and Exercise Metabolism (2018) (Mountjoy et. al. ‘International Olympic Committee Consensus Statement on Relative Energy Deficiency in Sport (RED0S): 2018 Update) recommended maintaining energy availability at ≥45 kcal/kg FFM/day for optimal health and performance.

In reality as not many of us really know what our Fat Free Mass is, this statement is not that helpful. For most athletes the best approach is to ensure that we are taking in enough energy in calories to match both our base metabolic rate (the energy we use just sitting, breathing) and to fuel our workouts. This may be achieved by keeping an accurate food diary and weight monitoring. Although please note weight loss does not have to occur for you to be suffering from RED-S.

It is important to use an individual approach which best helps you to maintain good nutrition without engendering feelings of stress or creating risks around disordered eating.

If food diaries and monitoring body composition can feed into disordered eating habits or be potentially a shaming stressful experience for you it can be useful to consider other, positive ways of monitoring energy availability.

Good methods that I find effective include:

• Monitoring performance - are you able to put out expected powers/paces for set intervals?
• Monitoring Energy availability - do you feel energised throughout the day? Do you have enough energy for your workouts and your day to day life tasks?
• Motivation - Is your motivation at usual levels for the stage you are at in your training block?
• Injury/illness - do you keep getting recurrent illnesses and injuries? This can be a sign of both over-training and under-fuelling.
• Heart Rate Responsiveness - is your heart rate responding normally to stimulus or is it unusually sluggish or high? This can be a sign of fatigue and if this cannot be accounted for by training load then you may be under-fuelling.
• Heart Rate Variability - this can also show undue stress on the nervous system caused by under-fuelling.
• Traffic Light System - find out more about this in John's video:

Early indicators of RED-S to watch out for include:

• Persistent fatigue
• Declining performance despite consistent training
• Disrupted sleep patterns
• Increased injury frequency
• Irregular or absent menstrual cycles in fertile female athletes who are not taking contraceptives
• Reduced training adaptation

2. Nutrition Timing

There is good evidence that strategic fuelling during winter training can help both performance and recovery; it will also help you to ensure you are eating enough:

Pre-workout

A meal with a combination of complex carbohydrates, lean protein and a small amount of fat 2-3 hours before training. If your are training over 3 hours after your meal a high simple carbohydrate snack 30-60 minutes before will be needed (banana, energy bar, dried fruit).

During

Aim 30-60g carbohydrates per hour for sessions >90 minutes. Drink 400-800ml/hour if your workout is over 30 minutes; remember you may not get the usual thirst signals in cold weather and indoors you may need more than usual due to higher sweat rates.

Post-workout

Protein (20-25g) + carbohydrates (this could be your usual meal or a snack). Current thinking is so long as this is within 2 hours of your workout this is sufficient but my current practice is to eat within 30 minutes to avoid leaving too long a gap and to ensure that the energy demands of the workout are adequately replaced. Also rehydrate, including electrolytes if needed. This will promote recovery.

3. Winter-Specific Considerations

Indoor training sessions may require more fluid intake due to greater sweat rate. Drink both during and after workouts and include electrolytes to optimise absorption.

Athletes who train outdoors in winter are more at risk of Upper Respiratory Infections so eating to support your immune system will help protect against this. This includes eating enough protein for your needs (1.6-2.0g/kg/day) and eating high quality fruits and vegetables to get all the vitamins you need to support immune function.

Higher intensity workouts and strength training require good fuelling in order to have their desired affect. Lower training volume does not necessarily mean you are in 'low training' or that you need to overly restrict your calories.

Practical Implementation for Winter Training

1. Training

Include adequate warm-ups to minimize injury risk (these may be done indoors even if you are training outdoors

Monitor intensity through power data and/or pace/speed and make sure thresholds are accurately set in your training applications on computer for a better idea of intensity. Heart rate is useful but less accurate for intensity and overall load in short high intensity workouts and strength training.

Strength training is simply difficult to categorise, so use a sensible approach and prioritise making strength gain to avoid muscle loss through calorie restriction and wasted sessions.

Build in recovery weeks every 3-4 weeks and eat to recover; ideally this would be eating to hunger; apps do not know how hard your body is working to recover.

2. Nutrition Strategies

Increase caloric intake to match the intensity as well as length of training sessions

Focus on a good, well balanced diet inclusive of protein, complex carbohydrates and some omega 3 and 6 fats; use the Athlete’s plate system to adapt your diet according to the demands of your training and/or eat to hunger.

Ensure you are adequately fuelled for all your training sessions before, during and after and that this energy is over and above your base metabolic rate (BMR).

Consider supplementation (Vitamin D, Iron) under professional guidance if blood tests show a deficiency

Do not go to bed hungry unless you are on a careful weight loss plan

If you do not need to lose weight and you are waking up in the middle of the night hungry you are probably not eating enough.

If you come back from a long endurance run or ride and want to eat all the contents of your fridge you probably did not fuel enough during the training.

3. Recovery Protocols

Prioritize sleep and sleep hygiene

Implement active recovery techniques - easy days where you do something you enjoy, some very light movement and relaxing activities.

Regular monitoring of resting heart rate and HRV

Eat a balance of protein and carbohydrates after your workout (within 30 minutes to 2 hours)

Eat regular meals with complex carbohydrates, some omega 6 and omega 3 fats, lean protein and lots of vegetables.

Professional Support

If you think you might have or be in danger of falling into RED-S you should seek support from:

• Sports Nutritionist
• Sports Medicine Physician
• Endocrinologist (if hormonal issues present)
• Mental Health Professional (if disordered eating patterns exist or have been a problem in the past)

Conclusion

Winter training presents certain unique risks for endurance athletes regarding energy availability and RED-S risk. Success lies in proactive monitoring, adequate fuelling, and appropriate training adaptations. Regular assessment and professional guidance can help athletes maintain health and performance during these demanding months.

References

- Mountjoy M, et al. (2018). IOC consensus statement on relative energy deficiency in sport (RED-S). British Journal of Sports Medicine

*Note: This article is for educational purposes. Individual athletes should consult healthcare professionals for personalized advice