In this review we summarized the role of glycogen availability with regard to performance and skeletal muscle adaptations for both endurance and resistance exercise. Most of the studies with low-glycogen availability focused on endurance type training.

The results of these studies are promising if the acute molecular response truly indicates skeletal muscle adaptations over a prolonged period of time. Unfortunately, these results on low-glycogen availability may be biased because many other variables including training parameters time, intensity, frequency, type, rest between bouts and nutritional factors type, amount, timing, isocaloric versus non-isocaloric placebo varied considerably between the studies and it is therefore difficult to make valid inferences.

Furthermore, the majority of the studies with low glycogen availability were of short duration [ 18 ] and showed no changes [ 11 — 17 ], or showed, in some cases decreases in performance [ ].

Nevertheless, reductions in glycogen stores by manipulation of carbohydrate ingestion have shown to enhance the formation of training-induced specific proteins and mitochondrial biogenesis following endurance exercise to a greater extent than in the glycogen replenished state [ 11 — 16 , 18 , 68 ].

For resistance exercise, glycogen availability seemed to have no significant influence on the anabolic effects induced by resistance exercise when MPS was measured with the stable isotope methodology. However, the exercise protocols used in most studies do not resemble a training volume that is typical for resistance-type athletes.

Future long-term training studies ~12 weeks are needed to investigate whether performing resistance exercise with low glycogen availability leads to divergent skeletal muscle adaptations compared to performing the exercise bouts with replenished glycogen levels.

The role of glycogen availability on skeletal muscle adaptations and performance needs to be further investigated. In particular researchers need to examine glycogen availability when endurance and resistance exercise are conducted concurrently, for example, on the same day or on alternating days during the week.

To date, only a few studies have investigated the interactions between nutrient intake and acute response following a concurrent exercise model. We recommend that future research in this field should focus on the following questions:.

What is the impact of performing one of the exercise bouts endurance or resistance with low glycogen availability on response of markers of mitochondrial biogenesis of the subsequent endurance or resistance exercise bout?

Does the resistance exercise bout need to be conducted with replenished glycogen stores in order to optimize the adaptive response when performed after a bout of endurance exercise? Is nutritional timing within a concurrent exercise model crucial to maximize skeletal muscle adaptations following prolonged concurrent training?

To conclude, depletion of muscle glycogen is strongly associated with the degree of fatigue development during endurance exercise. This is mainly caused by reduced glycogen availability which is essential for ATP resynthesis during high-intensity endurance exercise.

Furthermore, it is hypothesized that other physiological mechanisms involved in excitation-contraction coupling of skeletal muscle may play a role herein. On the other hand, the low glycogen approach seems promising with regard to the adaptive response following exercise.

Therefore, low glycogen training may be useful as part of a well-thought out periodization program. However, further research is needed to further scrutinize the role of low glycogen training in different groups e.

highly trained subjects combined with different exercise protocols e. concurrent modalities , to develop a nutritional strategy that has the potential to improve skeletal muscle adaptations and performance with concurrent training.

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Irving BA, Lanza IR, Henderson GC, Rao RR, Spiegelman BM, Nair KS. Combined training enhances skeletal muscle mitochondrial oxidative capacity independent of age. J Clin Endocrinol Metab. Whether you're a seasoned marathon runner or just starting on your fitness journey, giving your body the right nutrients after each run can accelerate your progress and improve your overall performance.

Crafting a recovery meal plan that includes a mix of carbohydrates, proteins, and fluids is the key to ensuring that your body bounces back stronger after each run. So, the next time you lace up your running shoes and hit the pavement, remember that what you eat after a run is just as important as the run itself.

Related: How long to wait after eating to run. Next Article How to cycle safely on the road Previous Article When to eat energy bars Total Endurance Nutrition Sam and Jules are Co-Founders and Directors of Total Endurance Nutrition , providing nutrition coaching and consultancy to endurance athletes.

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Previous Article When to eat energy bars. These are catabolic breaking down processes. Glycogen acts as a central glucose repository that the entire body can access via conversion of glycogen into glucose both in the liver and in the muscles. Muscle glycogen acts as a local storage site for the working muscles.

On average, there are g of glycogen in the liver and g in the muscle, and the body's glycogen stores hold about calories of energy, depending on the individual. As we know, glucose utilization by the working muscle can go up by fold during exercise, and yet after one hour, glucose is maintained at 4g at the expense of these muscle and liver glycogen reservoirs.

The amount of glucose in the blood can still be constant after two hours of exercise in well-nourished athletes. Tapping into these stores is important for exercise performance, but depleting these stores prematurely may cause premature fatigue or a drop in glucose leading to hypoglycemia.

This is why replenishing these glucose stores is key immediately after exercise especially when the next workout is close. The process of glycogen synthesis is also supported by other interesting metabolic changes that occur after exercise.

During the recovery anabolic window, in contrast to the predominant reliance on carbohydrate metabolism seen during a bout of moderate intensity exercise, the rate of lipid oxidation is accelerated and carbohydrate oxidation is reduced, even under conditions of high carbohydrate feeding.

Van Loon et al, Such a scenario following prolonged aerobic exercise has been shown to persist to the following morning. This shift in substrate metabolism demonstrates a state of high metabolic priority for muscle glycogen resynthesis , whereby lipid oxidation from intra and extra muscular sources is elevated to meet fuel requirements to sustain other processes not directly involved in recovery.

The importance of this is evidenced by the fact that there is a strong relationship between replenishment of liver and skeletal muscle glycogen stores and subsequent exercise performance.

Commencing a bout of exercise with reduced muscle glycogen levels impairs exercise capabilities, meaning that restoration of muscle glycogen is vital if optimal performance is desired. The primary trigger for glycogen synthesis refueling is carbohydrate ingestion.

In addition to replenishing carbohydrates-based stores, the body also has in place a set of processes to quickly repair the muscle damages induced by exercise. The biggest triggers of muscle protein synthesis repairing and building muscles are eating protein.

Appropriate doses of protein can maximally stimulate muscle protein synthesis. Given the main focus of this article we refer the interested reader elsewhere for further readings. The more correct answer? Within the first 2 hours, there is a key recovery window that can be used to maximize recovery and delaying ingestion of carbohydrates results in a reduced rate of muscle glycogen storage.

A bout of exercise influences glycemia both during and after, and this can persist for up to 48 hours post exercise due to changes in insulin sensitivity and muscle glucose uptake. Therefore, the post-exercise period includes everything from immediately post-exercise until 48 hours post-exercise and potentially longer if there is severe muscle damage or after exhaustive endurance exercise.

It is important to note, that in the real world, athletes compete or train much more regularly than every 48 hours, sometimes competing multiple times per day, depending on their event.

Therefore, the athlete must have a good understanding of which aspects of recovery they prioritize so that glycemia is optimal and energy substrates have recovered to facilitate future performance. The process of muscle glycogen synthesis begins immediately following exercise and is the most rapid during the first hours of recovery.

Glycogen synthesis after a bout of exercise occurs in a biphasic pattern, the insulin dependent and independent phases. In the initial post-exercise phase, there is a rapid increase in glycogen synthesis for mins. This is independent of insulin and reflects the initial recovery phase post exercise.

This initial rapid glycogen synthesis will slow if carbohydrates are not ingested. The above described insulin-independent phase, is suggested to occur when glycogen is depleted at the end of an exercise bout.

It seems that the mechanism responsible for the initial rapid phase of glycogen synthesis is the same contraction mediated glucose transporter type 4 GLUT4 translocation that turns glucose rushes into glucose rises when walking post meal. Additionally there is augmented glycogen synthase activity.

The second phase of glycogen synthesis has been defined as the insulin-dependent phase. Scott et al, Insulin increases blood flow to the muscle, GLUT4 translocation to plasma membrane, hexokinase II and glycogen synthase activity, which all contribute to increased glucose uptake by the muscle and glycogen synthesis.

Research in athletes has shown that the rate of carbohydrate delivery potentially can be augmented via certain strategies such as use of alternative carbohydrates, congestion of protein and caffeine.

Protein and carbohydrates work together in the post exercise window, allowing for improved protein metabolism as well as improved glycogen synthesis when compared to carbohydrates alone. Glycogen storage is not impacted by source of carbohydrates when comparing liquids and solids. In addition to carbohydrates, insulin secretion can also be induced through ingestion of certain amino acids.

This evidence led to the strategy of accelerating post-exercise muscle glycogen synthesis with the co-ingestion of carbohydrate and protein. However, when carbohydrate intake is adequate e.

Interestingly, inducing a glucose rush if this is in response to a carbohydrates-based meal can be an indication that your body is in an anabolic state, ensuring that glycogen stores are being refilled.

During this time phase, insulin is secreted to support glucose uptake by the cells but also protein synthesis in the muscles. This is perhaps why the co-ingestion of protein and carbohydrates have synergistic effects above caloric matched ingestion of one or the other individually.

Yes, you read that right, whilst generally you want to stay in the blue zone, and this is possible even with higher carbohydrate intakes when changing meal order or altering meal composition a little to include fibre and some fat, for example, a bit of a spike post meal in the window of time post workout is probably not detrimental.

Your carbohydrate requirements are at least in part related to your intake prior and during training — in your Prime and Perform windows.

Beyond this, they are dictated by the intensity and duration of your activity, with consideration given to whether you want to optimize recovery or intentionally not do so.

It should be recognized that these recommendations are in the context of total output for a week as well as after one training session, as is the nutritional intake.

With respect to protein, dosing is more related to maximal muscle protein synthesis than total dosing requirements. As caloric intake increases, protein will naturally go up.

The requirements of protein to ensure maximal muscle protein synthesis vary based on age, energy intake more protein is needed in times of energy restriction and recent training stimulus resistance training increases muscle protein synthesis.

When planning multiple sessions per day or multiple sessions with a short time between, rapid restoration of glycogen stores may be required. If this is the case and recovery time is less than 4 hours, you may consider the following right after your workout:.