Training for definition: myths and facts

«Right now I’m bulking, but in the summer I’ll start training for definition» — a phrase you can hear in any gym. Behind it lies the notion that there are special workouts that «carve out» the muscles. Our editorial team checked the most popular beliefs about muscle definition against the research and explains what a clear muscular shape actually depends on.

What definition is from a physiological standpoint

Definition is the visibility of the contours of the muscles under the skin. It depends on two independent factors: the size of the muscles themselves and the thickness of the subcutaneous fat layer over them. A large muscle under a thick fat layer looks massive but not defined. A thin fat layer over small muscles gives a lean but unremarkable appearance.

It is important to understand that a muscle cannot become «harder», «firmer» or «carved» from a special way of training. A skeletal muscle can only increase in volume or decrease. What is colloquially called «tone» is a combination of sufficient muscle mass and a low fat percentage, not a separate quality of the tissue.

So «training for definition» as a separate category does not exist from a physiological standpoint. There is training that preserves or builds muscle, and there is an energy deficit that reduces fat stores. Definition is the result of the combination of these two processes.

Appearance is additionally affected by genetics (the distribution of fat deposits, muscle shape, tendon attachment sites), the body’s water content and even lighting. «Before and after» photos on social media often use all these factors, so you should be careful comparing yourself with them.

The myth of spot fat reduction

The notion that exercising a certain body area burns fat exactly there is one of the most persistent myths of fitness. Hence the hundreds of crunches for «abs» or arm extensions for «toned» triceps. Unfortunately for fans of such programs, research does not support it.

In a randomized study by Vispute and colleagues (2011), participants did abdominal exercises for six weeks. The strength of the abdominal muscles increased, but neither the fat percentage in the abdominal area nor the waist circumference changed significantly compared with the control group. The abs became stronger, but under the fat layer this was not visible.

A study by Ramírez-Campillo and colleagues (2013) with training of only one leg showed an even more interesting result: fat mass decreased, but mainly in the upper body rather than in the trained leg. The body mobilizes fat from its depots according to a genetically determined distribution, not by the principle of «where the muscles work».

Lipolysis — the breakdown of fats — takes place in fat tissue under the influence of hormones that circulate in the blood throughout the body. Fatty acids are then transported to the muscles, which use them. So a working muscle does not predominantly «pull» fat from the neighboring subcutaneous tissue.

• Myth:crunches burn fat on the belly.Fact:they strengthen the muscles but do not reduce fat locally.
• Myth:each problem area needs its own exercises.Fact:fat decreases systemically, and the order is determined by genetics.
• Myth:«problem areas» can be made to slim down first.Fact:they usually decrease last, and that is normal.

«Light weights and lots of reps»

The classic advice: «when bulking, work heavy; for definition, light weights for 15–25 reps». The logic is supposedly that high-rep work burns more calories and «carves» the muscles. In fact, the energy expenditure of a strength workout is relatively small compared with the daily balance, so changing the rep range has little effect on fat mass.

Reducing weights, on the other hand, can have negative consequences. On an energy deficit the main goal of strength training is to signal the body that the muscles are needed. A meta-analysis by Schoenfeld and colleagues (2017) showed that hypertrophy is similar across a wide range of loads, but strength is better maintained when working with heavy weights. Giving up heavy work during a deficit often leads to a rapid loss of strength.

Studies on maintaining training adaptations, in particular the work of Bickel, Cross and Bamman (2011), showed that muscle mass and strength can be preserved even with a substantial reduction in volume if intensity (the working weight) stays high. So on a deficit it is intensity that is the most important parameter to preserve.

This does not mean that high-rep sets are useless. They can well be part of a program, especially in isolation exercises. But the basis of training on a deficit should be the same compound movements with the same or close weights as during a bulk.

Fasted cardio, sweating and other common advice

Fasted cardio in the morning is considered a secret weapon for definition: without carbohydrates the body supposedly burns more fat. During the workout itself the share of oxidized fat may indeed be higher. However, a study by Schoenfeld and colleagues (2014), which compared fasted and fed cardio against the same deficit, found no difference in fat-mass reduction after four weeks.

The explanation is simple: the body compensates for the distribution of fuel over the course of the day. If more fat is burned in the morning, then more carbohydrates will be used later, and vice versa. For the overall result, what matters is energy balance over days and weeks, not fat oxidation over a single hour.

Thermal belts, «sauna suits» and training in warm clothing are another popular myth. They increase sweating, and the weight on the scale after a workout is indeed lower, but this is a loss of water that returns after the very first glass of fluid. At the same time, such an approach raises the risk of overheating and dehydration.

Another piece of advice is «supersets and circuit training for cutting». Circuit training is useful for endurance and saving time, but because of the shorter rest the quality of the main sets decreases. If working weights in the compound exercises drop because of this, the benefit for definition is doubtful.

What really works: a strategy on a deficit

The basis of definition is a moderate energy deficit, that is, a steady intake of somewhat less energy than is expended. The recommendations of Helms, Aragon and Fitschen (2014) for natural athletes preparing for competition advise a rate of weight loss of about 0.5–1% of body weight per week to minimize muscle loss.

The second key factor is sufficient protein intake. A randomized study by Longland and colleagues (2016) showed that on a strict deficit combined with intense training, the group with high protein intake (2.4 g/kg per day) not only lost more fat but also gained lean mass, whereas the group with lower protein (1.2 g/kg) merely preserved it.

1. Create a moderate calorie deficit and control the rate of weight loss.
2. Increase protein intake — it protects the muscles and provides good satiety.
3. Continue strength training with heavy weights in the compound exercises.
4. Add moderate cardio and increase daily activity (steps).
5. Watch sleep and recovery — on a deficit they matter more than usual.

The training program on a deficit can stay the same as during a bulk. If recovery worsens, it is sensible to reduce volume a little — the number of sets — but keep the working weights. It is precisely this signal that best protects the muscles under a shortage of energy.

Be realistic about timelines. Going from a moderate level of fat to pronounced abdominal definition can take several months of consistent work. Too fast a pace and extreme diets lead to muscle loss, a drop in strength, worse well-being and, often, a rebound in weight after the «cut» ends.

Editorial conclusions

A separate «training for definition» does not exist: definition is the combination of sufficient muscle mass and a low level of subcutaneous fat. Spot fat reduction through exercises for a certain area is not supported by research.

On a deficit, strength training should keep a high intensity — this is the main signal for preserving muscle. Light weights for many reps, fasted cardio and thermal belts provide no advantage in reducing fat.

What really works is the combination of a moderate calorie deficit, high protein intake, heavy strength training, moderate cardio and patience.

We also recommend reading our articles on HIIT for fat burning, on cardio during a bulk and on the three-day split.

References

1. Vispute SS, Smith JD, LeCheminant JD, Hurley KS. The effect of abdominal exercise on abdominal fat. J Strength Cond Res. 2011;25(9):2559–2564.
2. Ramírez-Campillo R, Andrade DC, Campos-Jara C, et al. Regional fat changes induced by localized muscle endurance resistance training. J Strength Cond Res. 2013;27(8):2219–2224.
3. Schoenfeld BJ, Aragon AA, Wilborn CD, et al. Body composition changes associated with fasted versus non-fasted aerobic exercise. J Int Soc Sports Nutr. 2014;11:54.
4. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20.
5. Longland TM, Oikawa SY, Mitchell CJ, et al. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr. 2016;103(3):738–746.
6. Bickel CS, Cross JM, Bamman MM. Exercise dosing to retain resistance training adaptations in young and older adults. Med Sci Sports Exerc. 2011;43(7):1177–1187.
7. Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis. J Strength Cond Res. 2017;31(12):3508–3523.