I have tried to determine the optimal length of time a training session should be and why. I can remember reading a Paul Chek article that said it should be 40 minutes, but it had no back up research or scientific facts to go with it. Please help.
This question is a vague one and requires more information to be answered effectively, but you can get some mileage out of this. Be sure to check out the references for further info.
It’s important to note that your clients’ goals will be a major factor. This will dictate the modulation of every exercise variable, which will in turn dictate total training time. Also, read the paragraph at the end on stress. This will be the single most important factor in determining optimal time length for a training session. I hope the following sheds some light for you.
The basic principle behind the optimal length of training time is related to hormonal profile responses in the body during exercise. The majority of fitness professionals in the industry will be working with individuals who want to lose weight and increase lean tissue (tone up). It is well known that an anabolic profile is preferred to achieve these results. In order to obtain an anabolic profile in an individual, his or her system should be stressed with moderate to high intensity exercise to illicit that hormonal response during exercise. (Note: Intensity level will be completely relative to the client.)
The sympathetic nervous system or the "fight or flight" branch of the autonomic nervous system releases a cache of hormones during the first 10 to 15 minutes of exercise to stimulate the body to perform by shuttling blood to working tissues, dilating the bronchials, excitation of brain function, etc. The particular hormones that are relevant to the fitness professional are the anabolic hormones (testosterone, growth hormone, etc) and the catabolic hormones (glucocorticoids-cortisone, cortisol, etc).
- Resistance training using multi-joint exercises such as squats, bent over rows and deadlifts are best for spiking an anabolic profile. Cardiovascular training utilizing intensities of 75 percent or more with an interval type of component to it is another option.
- Traditional sustained cardiovascular training and/or resistance training involving 30 or more performed repetitions per set per exercise are best for inducing a catabolic profile.
The sympathetic nervous system begins to decrease activity after about 60 minutes. This will vary depending on the individual’s intensity and hormonal health. After that drop, the demand of energy required to continue activity surpasses the anabolic profile's capability to be efficient and stresses the system. This is where gluco-corticoids come in; their job is to deal with stressors. The most relevant hormone in this class is cortisol. During stressful or prolonged bouts of exercise, cortisol performs the following biological actions:
- Increases protein degradation in muscle and connective tissue
- Decreases protein synthesis in muscle and connective tissue
- Decrease amino acid transport to muscle
- Increases facial lipogenesis and fat deposition
- Decreases immune system mediators: cytokines, eicosanoids, T-lymphocytes
- Increases vasoconstriction
- Increases and decreases mood (euphoria and depression)
- Increases brain impulse for food intake
The rationale behind keeping an exercise program under an hour is that you want to stay as anabolic as possible. Many of the renowned fitness experts utilize this protocol (Jerry Telle, Paul Chek Charles Poliquin, to name a few). If you exercise for prolonged periods of time or go into an aerobic state, your hormonal profile will begin to convert to the stress class of hormones to keep up. If you consider the average person who tries to lose weight by doing a bunch of cardio and/or performing two hours of weights, their body composition and progress begin to move in the same direction as their favorite 6:00pm elliptical or treadmill, which is nowhere.
It is also important to note that full adaptation of either hormonal profile is not achieved when cardiovascular training and resistance training are mixed during a session.
If you consider that the anabolic profile from resistance training drops off around the 60-minute mark, by keeping a training session between 30 to 45 minutes, you’re behind the drop point in the curve; in other words, the individual will still be going anabolic as they're walking out of the gym. I have found this approach to work the best.
Determining the optimal length of time a training session should be is dependent upon the person you are training. The major component you must determine is the stress level of each individual. Stress accumulates in the body and becomes undifferentiated, and you have to make sure that your training session is part of the solution and not contributing to the problem. This factor alone will dictate the concepts mentioned above and will be essentially different for everyone.
Some of the people you train may be so stressed out and physiologically exhausted from poor diet and personal stress (physical, mental, emotional, spiritual) that a general battery of multi-joint and/or single joint exercises will detract from a person’s vitality and just be another stress to a stressed system. The more stressed a person is, the more impaired their hormonal system will be. Stretching, deep tissue and chi or energy building type of exercise is needed for highly stressed individuals. I have had some clients for an hour session that were so stressed, 45 minutes were spent stretching and doing rhythmical activities such as walking and tai chi to off set their catabolic system and stimulate anabolism and maybe 15 minutes was spent on actual weight training exercise. Everyone will react differently.
- Borer, K. Exercise Endocrinology. Human Kinetics Publishers, 2003
- Chek, P. Program Design. Encinitas, CA: C.H.E.K Institute, 1995
- Program Design - Part 1. Audio Clinics. Personal Training on the Net