|A Case for Carbs Before Morning Training
Len Kravitz, Ph.D.
Naharudin, M.N.B., Yusof, A., Shaw, H., et al. (2019). Breakfast omission reduced subsequent resistance exercise performance. Journal of Strength and Conditioning Research, 33(7), 1766-1772.
A question personal trainers get regularly from clients is should they eat breakfast prior to a morning resistance training session. Some clients simply choose to skip breakfast before a workout. Others may be actively engaged in an intermittent dietary approach, weight loss strategy or health plan which places them in a fasted stated for their morning workout. The question how omitting breakfast prior to a resistance training session affects muscular performance has not been investigated until just recently. Designing a study with two resistance trainings trials, Naharudin and colleagues (2019) tested the influence of eating breakfast or no breakfast on muscular performance.
Sixteen non-smoking, resistance-trained men (age = 23 years; BMI = 25.3 kg/m2) were recruited for this study. All participants had at least two years of resistance training experience where they completed at least 2 workouts/week during that time. Only participants who regularly performed back squats and bench presses in their training were included in the study. Additionally, only participants who regularly ate a breakfast (at least 3 times/week) were included in this study.
At the pre-study meeting participants learned the details of the study and completed requisite human consent forms and other screening materials. Then, following a 5-minute cycling warm-up and 5-minute self-selected exercise specific warm-up, the participants completed a 10-repetition maximum (10RM) in the back squat followed by a 10RM in the bench press. Using a 'trial and error' approach, each participant progressively increased the lifting load on the back squat and bench press until an accurate 10RM weight was determined.
Experimental Resistance Training Trials With or Without Breakfast
For the two experimental trials, with or without breakfast which were separated by 3 days, each participant arrived to the testing laboratory (between 8am and 9am) after an overnight 10hr fast (and sleep). For the trial with the breakfast, each participant consumed a standardized meal consisting of milk, cereal, rice, bread, butter, jam and orange juice. The meal provided 1.5 grams of carbohydrate per kilogram of body mass for each participant. During the breakfast omission trial, each participant consumed water equivalent to the total water content of the breakfast meal. Meals were consumed over a period of 10 minutes, which were followed by 2-hour seated rest in the laboratory.
For each trial the participants performed a 5-minute cycling warm-up followed by
5 minutes of self-selected stretching and exercise-specific warm-up movements. Then, each participant completed 2 warm-up sets of 10 repetitions at 30% and 60% his 10RM on the back squat and bench press. Next, the participants completed 4 sets to failure of both the back squat and bench press at 90% of each subject's 10RM. After each set the participants rested for 3 minutes.
Results of the Study
Since the weight lifted on the back squat and bench press was the same for both trials (breakfast versus no breakfast) the total repetitions completed was the primary variable for comparison. On the back squat the participants completed 15% lower (i.e., 10 fewer squat repetitions over the 4 sets) during the no breakfast trial. Specifically, back squat repetitions in sets 1 and 2 were lower during the no breakfast trial while repetitions in sets 3 and 4 were not different.
Total repetitions completed for the bench press were 6% lower (i.e., a reduction of 3 repetitions) during the no breakfast trial. Similar to the back squat, repetitions in sets 1 and 2 were lower during the no breakfast trial while repetitions in sets 3 and 4 were not different between the breakfast and no breakfast trials.
Major Take-Away from this Study
The key finding of this study is that muscular performance during the no breakfast trial for the back squat and bench press was 15% and 6% lower, respectively. Thus, for optimal muscular force production in a morning workout, Naharudin et al. (2019) encourage athletes and enthusiasts to eat a breakfast. The researchers go further, suggesting for optimal performance the breakfast should be a high-carbohydrate meal. This leads to the follow-up discussion why this meal nutrient content approach may be best for optimal muscular performance.
Evidence Why a High Carbohydrate Breakfast Is Best for Muscular Performance
An important fuel for optimizing resistance training performance is the stored glycogen in muscle. In an early scientific review on carbohydrate supplementation, Haff et al. (2003) summarize that the evidence strongly suggests that resistance training, especially using large-muscle mass exercises performed with high training volumes with moderate loads, is pretty dependent upon muscle glycogen stores. Haff and colleagues further state the amount of muscle glycogen used in large-muscle exercises is related to the total amount of work accomplished during the resistance-training bout. For instance, Robergs et al. (1991) demonstrated that 6 sets of 6 repetitions of leg extension exercise at 70% 1RM resulted in a 38% reduction in glycogen content of the vastus lateralis. In their review on fatigue from intermittent exercise, Lambert and Flynn (2002) propose that when performing multiple bouts of high-intensity resistance exercise, muscle glycogen will reach a level where it is no longer able to sustain ATP production for the demanding work. Thus, fatigue resulting from glycogen depletion will ensue. Lambert and Flynn summarize to increase the amount of work performed in an exercise session, some type of dietary supplementation (i.e., breakfast if it is in the morning) to increase carbohydrate availability is recommended.
Side Bar 1: Ten Facts about Breakfast!
Ten facts and/or misconceptions about breakfast are answered from the data presented in a review article on the effect of breakfast on appetite regulation, energy balance and exercise are addressed here (Clayton and James, 2015).
1) People who regularly omit eating breakfast tend to have higher BMIs.
2) Omitting breakfast is associated with an increase in prevalence of obesity-related chronic diseases such as type 2 diabetes and coronary heart disease
3) People who eat breakfast have healthier lifestyles.
4) People who eat breakfast have a reduced consumption of snacks.
5) Although people who omit breakfast tend to eat a little more at lunch, the increase in food consumption does not fully compensate for the calories omitted at breakfast.
6) Individuals performing exercise in the morning should aim to consume breakfast 1 to 4 hours before exercise in order to avoid any deleterious affects to the workout.
7) An overnight fasting (i.e., during sleep) results in approximately a 40% reduction in liver glycogen.
8) People who omit eating breakfast tend to lower their resting metabolic rate up to the point when a lunch (or next meal) is eaten.
9) The breakfast meal typically equates to 20-35% of the daily energy requirements for a man or woman.
10) People aiming to maximize exercise performance, who do not wish to eat a breakfast, will improve their workout with a carbohydrate drink.
Bio: Len Kravitz, PhD, CSCS, is the program coordinator of exercise science at the University of New Mexico, where he received the Outstanding Teacher of the Year and Presidential Award of Distinction. He just released his third book, HIIT Your Limit: High-Intensity Interval Training, (Amazon).
Clayton, D.J., and James, L.J. (2015). The effect of breakfast on appetite regulation energy balance and exercise performance. Proceedings of the Nutrition Society, 1-9.
Haff, G.G., Lehmkuhl, M.J.,McCoy, L.B., and Stone, M.H. (2003). Carbohydrate supplementation and resistance training. Journal of Strength and Conditioning Research, 17(1), 187-196.
Lambert, C.P. and Flynn, M.G. (2002). Fatigue during high-intensity intermittent exercise. Sports Medicine, 32(8), 511-522.
Robergs, R.A., Pearson, D.R., Costill, D.L. et al. (1991). Muscle glycogenolysis during differing intensities of weight-resistance exercise. Journal of Applied Physiology, 70(4), 1700-1706.