You Need to Fuel Strength Training Differently. Here’s How to Do It Right.

A sports-certified Registered Dietitian lays out how to fuel during a strength-focused training block (and no, you don't have to choke down a million protein shakes).


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In the off-season, many triathletes head to the weight room for a strength-focused training block. Strength training is a different stimulus for the body than the aerobic nature of swim-bike-run, and therefore requires a different kind of fueling. Most people associate weightlifting with protein powders, and for good reason: dietary protein triggers the metabolic adaptation and rebuilding of muscle, a process known as muscle protein synthesis (MPS). But eating for strength is not quite as simple as just eating more protein.

The nutrition strategies for muscle building and strength are complex and interrelated. To get the most out of your work in the weight room, lean into these important factors when planning your strength training and daily diet.

RELATED: Strength Training for Triathletes

Timing of protein intake

Not only is it critical to meet your daily protein and energy needs, but the timing of protein and carbohydrates is key to optimizing strength gains and recovery. 

The window of anabolic opportunity begins in the hour before a strength session and lasts up to 24 hours after resistance training.  

Pre-workout

Consume 15-20g protein, 25-50 grams of carbohydrates (carbs), and 16-24oz of water in the hour before resistance training. If an aerobic endurance session follows your resistance training, increase carb intake to kickstart glycogen replenishment.

During a workout

Fueling during a strength session depends on whether you are coming from an endurance session, missed the pre-workout snack, or are going into an endurance workout next. Generally, it is not necessary to fuel during a session unless you need some energy. In that case, a sports drink with carbohydrates is a good idea. Regardless, plan on bringing water and always start your workout well-hydrated. 

Post-workout

To enhance muscle repair, accelerate glycogen repletion, and promote favorable changes in body composition, plan for a snack or meal containing both protein and carbohydrate.

In the early recovery phase (0-45 minutes after a workout), consume 15-25 grams of protein along with 25-50 grams of carbs and 20 ounces of fluid per pound of weight lost during the session. It’s worth noting that consuming more than 40 grams of protein at once has not been shown to enhance the muscle rebuilding response. Just because the body-building world glamorizes the consumption of protein, more is not necessarily better. If you consume more protein than is needed, the extra protein is either burned for energy, which is not very efficient, or stored as fat, which is likely not desirable. 

Your nutritional choices around training are often influenced by convenience and practicality. Unless you are going into a meal, aim for on-the-go food such as Greek yogurt with fruit, peanut butter and honey or jelly sandwich, low-fat cheese, and crackers, chocolate milk, or a protein bar. 

RELATED: Everything Triathletes Need to Know About Protein Powders

Daily Nutrition

Since muscle protein rebuilding is ongoing for at least 24 hours, consuming adequate nutrition to support MPS long after the workout is recommended. 

The athlete’s size and age are determining factors in how much to consume at one time. Smaller athletes’ may need only 15-20g, whereas larger athletes with more muscle mass and higher energy output can easily incorporate up to 30-35g protein at one meal. Older athletes (>55-60 years old) require more protein to achieve the same effect due to the progressive loss of muscle mass associated with the aging process.

RELATED: How Much Protein Does a Triathlete Need Each Day?

To maximize physical adaptation and maintain a robust immune system, the timing and amount of protein/carbohydrate are critical. Here is a general guideline.

Meals

Include protein at each meal (15-35 grams, depending on size and age of athlete).

Snacks

Bridge the gap between meals that are more than four-five hours apart. Include 10-15g of protein in snacks.

Bedtime snack

Dairy protein (made up of whey and casein) is ideal due to casein’s slow-releasing nature and the fast-releasing nature of whey. In addition, the whey/casein pairing supports muscle building/repair during the overnight fast.

Photo: Getty Images

Maintain positive energy balance

The breaking down and rebuilding of muscle tissue is energy-consuming, so falling short on calorie requirements will impair your recovery rate, ultimately jeopardizing health and metabolic function. When fuel stores (glycogen) run low and the body is in an energy deficit, it turns to protein for fuel by breaking down muscle for energy. Therefore, consuming adequate calories, particularly from carbohydrates, to meet energy expenditure is important to spare unnecessary muscle breakdown. As an example, an intense strength session may deplete 30 percent of glycogen stores depending on the intensity and duration. When this type of training is combined with endurance training (albeit shorter this time of year), glycogen stores can become significantly depleted if you aren’t diligent about fueling around your training.

Optimal protein choices

High-quality protein is the most effective for the maintenance, repair, and synthesis of skeletal muscle protein. Low-fat dairy products, lean meats, eggs, and whey protein all contain essential amino acids, the most potent stimulators of MPS. On a grading scale, whey protein is superior to soy, and soy is more effective than casein in promoting protein synthesis.

The poster child of all protein powders, whey, makes up 20% of milk’s protein and is easily digestible and rapidly absorbed. Whey’s notoriety stems from having the highest amount of leucine, a branch chain amino acid (BCAA) known as the anabolic trigger of muscle repair and growth in response to training.

Casein accounts for 80% of cow’s milk protein and is slow absorbing, can be harder to digest, and has a lower leucine content, leaving whey at the top of the protein chain post-workout.

RELATED: Why the Type of Protein You Consume Makes a Big Difference

Animal Protein Food Sources
Cottage cheese, 1/2 cup 13g
Greek yogurt, 5 oz 11-20g
Milk, 8 oz 8g
Cheese, 1 oz 4-7g
Beef, chicken, fish, 1 oz 7-8g
Egg 6g
Ground Turkey, 1 oz 7g

Plant Proteins

Most plant-based proteins are called “incomplete” because they lack some of the nine essential amino acids. Notable exceptions are soy, pea, and hemp protein powders, as they contain all the essential amino acids, though still lower in leucine content than whey. As long as plant protein is consumed in higher doses from various sources, protein needs can be sufficiently met with plant proteins. When taking this recovery route, the best strategy is mixing different plant proteins.

RELATED: Yes, You can Make Muscle on Plant Protein

Plant Protein Food Sources
Tofu, 1/2 cup 8g
Tempeh, 3oz 15g
Spirulina (seaweed), 2 tbsp 8g
Lentils, 1/2 cup 9g
Nuts, 1 oz 4-6g
Nut butter, 2 tbsp 8g
Edamame, 1/2 cup 8g
Photo: Getty Images

Should I take a protein supplement?

Athletes are often enticed by the elixir of supplements as if they are a cure-all above food. And let’s be honest, the number of choices on the market is overwhelming – specifically those containing protein from various sources. Certainly, there is a time and place for protein supplementation but keep in mind, the timing of protein intake is vital.

Picking the best protein powder

As a rule, it’s best to get your protein from food, whether animal or plant, but when on the go, the convenience of protein supplementation can’t be underestimated. That’s why many athletes rely on protein powder for the ultra-convenience factor and to ensure they have enough in their diet. It’s easy to prepare, travels well, can be stored at room temperature for up to one year, and often cheaper gram for gram. But you don’t want to sacrifice quality, so knowing the lay of the protein powder land is wise.

Whey protein isolate

Contains 90% protein, is the least processed, more expensive, lower lactose content.

Whey protein concentrate

Contains 30-80% protein, contains some lactose (milk sugar), and fat, cheapest form of whey.

Whey hydrolysate

Pre-digested whey protein, faster absorption, most processed, has a bitter flavor, and most expensive. Best for sensitive stomachs.

Casein protein

Best option for overnight muscle repair/build or bridge the gap between extended meals. It can be harder to digest than whey protein and is known as the “slow” digesting protein. Found in dairy sources.

Soy protein

An excellent source of high-quality plant protein, good option for vegetarians/vegans.

Pea and Hemp Protein

A complete plant protein and a good option for vegans, vegetarians, or those allergic or sensitive to whey or soy.

Most protein powders contain 20-25g of protein per scoop. Keep in mind more is not better.

What about other dietary supplements?

There are many other dietary supplements marketed to athletes with a strength training focus. These include BCAAs, creatine, sodium bicarbonate, Beta-Hydroxy-Beta-Methylbutarate (HMB), B-Alanine, and more.

At a glance, these ergogenic supplement claims sound too good to be true – and in many cases, they probably are. Before whipping out your credit card, consider that a well-balanced and timely diet of protein, carbohydrate, and fat provides all the necessary ingredients for muscle growth and strength. When buying supplements, there is a risk of cross-contamination or mystery ingredients left off the label. An athlete seeking to gain muscle and strength during the off-season is best served to follow the food-first mantra in the pursuit of health and performance. The best nutritional recommendation for MPS is to consume sufficient high-quality protein and a positive energy balance in meals and snacks. 

Susan Kitchen is a Sports Certified Registered Dietitian, USA Triathlon and Ironman Certified Coach, accomplished endurance athlete, and published author. She is the owner of Race Smart, an endurance coaching and performance nutrition company that works with athletes across the globe as they strive toward optimal health, fitness, and performance.