Intensity

In every gym you can find people that go through their training routine with the same exercises, repetitions and sets. With all the well paid top athletes it is only normal that our scientific community studies the best number of sets – repetitions and intensity, to meet the different goals of the athletes. Of course most gymgoers also have ideas on this subject.

The general thinking comes down to:

General Fitness (fitnessers) 8 – 15 repetitions per set

Strength (powerlifters) 1 - 6 repetitions per set

Muscle Mass (bodybuilders) 8 - 12 repetitions per set and to pack on muscle mass for slow twitch fibers (such as thighs and calves) - 12 - 20 or more reps per set.

High Intensity Training (HIT) one set to failure for each muscle group

Maximum Strength (strongmen) 3 – 5 with ˃ 90% 1RM

Many people still believe that a high workload with many sets and reps and little rest, will increase endogenous (body own) testosterone, growth hormone and other anabolic hormones, even now numerous recent studies are showing that exercise-induced increases in systemic hormones do not help in muscle growth.

Mangine et al 2015: “The similar responses of testosterone and IGF-1 observed between the training protocols, at both week 3 and week 10, suggest that differences in acute program variables (i.e., intensity, volume, and rest) may not stimulate significant differences in the response of these anabolic hormones when assessed only the first and last week of an 8-week training program. Previous investigations have reported a similar testosterone response following both heavy (3–6 RM) and moderate (9–10 RM) loading”

Most professional Iron Warriors nowadays don’t respect these training protocols and change protocols often to prevent adaptation. But for the lesser gods and the natural training athlete, knowing what will work best to meet our goals is still important thus let’s take a look at some recent studies.

The effect of training volume and intensity on improvements in muscular strength and size in resistance-trained men. Mangine et al 2015:

“ In conclusion, the results of this study indicate that high-intensity (3–5 RM), low-volume resistance training program utilizing a long rest interval (3 min) is more advantageous than a moderate intensity, high-volume (10–12 RM) program utilizing a short rest interval (1 min) for stimulating upper body strength gains and muscle hypertrophy in resistance-trained men during an 8-week study. Furthermore, the strength and morphological improvements demonstrated did not appear to be influenced by the endocrine response. These observations question the utility of high-volume training programs that are designed to maximize the acute hormonal response as being ideal for stimulating muscle growth, at least during a relatively short duration of training.

Emphasizing training intensity over volume may provide an advantage for accelerating muscle growth and strength gains in a short-term training cycle.”

Types of Competitive Lifters

In addition to longitudinal resistance exercise training studies, insight on the long-term training effect on muscle fibre characteristics may be extrapolated from descriptive studies of athletes from the competitive lifting sports: weightlifting, powerlifting and bodybuilding. Athletes in each of these sports utilise heavy resistance exercise to permit optimal adaptations for their respective sports.

Weightlifters

Weightlifting, also known as Olympic-style weightlifting, is the only competitive lifting sport contested in the Olympic Games, and is the most popular lifting sport in most parts of the world. The two lifts contested are the snatch, and the clean and jerk lifts. Both of these lifts are characterised by extremely high levels of power. While heavy loads are lifted by elite heavy weight lifters (e.g. >250kg for the clean and jerk; >200kg for the snatch), very high barbell velocities are also observed (e.g. >2 m/ sec). Athletes excelling in this sport often use very high relative intensities (>90% 1RM), with increased intensities most apparent as major competitions approach. Repetitions per set are often fairly low due to the importance of maintaining proper lifting technique (i.e. ≤5 repetitions), while inter-set rest intervals are often up to 3 minutes for the heaviest loads to permit adequate recovery be-tween sets.

Powerlifters

Powerlifting is the most popular lifting sport in North America. Athletes compete in three lifts: (i) the barbell squat; (ii) the bench press; and (iii) the dead lift.^[18] Maximal efforts for each of these lifts are characterised by extremely heavy loads and low velocities. For example, world records for heavy-weight powerlifters exceed 450kg for the squat, 320kg for the bench press and 410kg for the dead lift. In many ways, powerlifters train in a some-what similar manner to weightlifters, although the absolute loads are greater and the velocities are much lower.

Body Builders

Success in the sport of body building is primarily based on muscular hypertrophy, although muscular symmetry, leanness and presentation style are also critical. Although actual lifting is not part of competition, athletes in this sport train extensively with heavy resistance exercises. Training programmes are typically of very high volume (i.e. total number of repetitions) and often utilise relatively lower training intensities when compared with weightlifters or powerlifters. In addition, body builders tend to use more small muscle mass and single-joint exercises than do athletes in the other lifting sports.

Muscle Characteristics of Competitive Lifters

Comparing the skeletal muscle characteristics of these competitive lifting populations can help shed light on the role of training load. While the number of studies on these athletes is limited, important training-related information may be deduced.

Fibre Types

Figure A illustrates the fibre type profiles for weightlifters, powerlifters and body builders. Although few studies are available on elite level athletes in these sports, it appears that weightlifters and powerlifters have a greater percentage type II fibres than type I fibres. On the other hand, the limited data for body builders indicates an opposite pattern, that is a greater percentage type I fibres than percentage type II fibres. It is beyond the scope of these cross-sectional studies as to whether these differences are due to the long-term training programme, or if there is a genetic predisposition for these respective fibre characteristics. However, it should be noted that the athletes who require great levels of muscular force and power (weightlifters and powerlifters) are the ones who also possess the greatest content of the fibres capable of producing the greatest force and power. This ability to produce high force and power is due to both the size of the fibre, the fibre type and the contractile protein isoforms present.

Percentage Fibre Type Areas

As seen in figure B, the percentage cross-sectional area for type II fibres is considerably greater than for type I fibres for weightlifters and power-lifters. The opposite pattern is seen for body builders. When figures A and B are compared, it is evident that there is a preferential hypertrophy of the type II fibres for the weightlifters and powerlifters, while the body builders have succeeded in increasing the size of both type I and type fibres equally.

As figure B illustrates, the weightlifters and powerlifters who routinely train with loads ≥90% 1RM exhibit the greatest growth in the type II fibres. This adaptational difference is less apparent as the relative intensity decreases. Body builders who typically perform a greater number of repetitions per set and much shorter inter-set rest intervals appear to stimulate muscle growth equally in both fibre types. This would be advantageous for a sport dependent on muscle hypertrophy. It is not known if body builders would experience even more hypertrophy of type II fibres if they also included more resistance exercise at very high relative intensities. Furthermore, it has been shown that large muscle mass, multi-joint exercises (i.e. barbell squats) elicit a greater anabolic hormone response than small muscle mass, single joint exercises (i.e. leg extensions, leg curls, hip/back extensions) even when relative intensities are equated. Thus, it may also be advantageous for body builders to maximise muscular growth by incorporating more large muscle mass, multi-joint exercises into their training programmes. Further study on these aspects of the training programmes are warranted.

Fibre Type Area Ratios

Perhaps most telling is the difference between weightlifters and powerlifters compared with body builders for the ratio of type II/type I fibre areas. This method of expressing muscle fibre characteristics permits one to see the combined effects of both percentage fibre type and percentage fibre type cross-sectional areas. Figure C illustrates the type II/type I area ratios for successful competitive lifters. Both weightlifters and powerlifters have a considerably greater ratio compared with bodybuilders, again suggesting a preferential hyper-trophy of the type II fibres for the type of training they perform. These data do not mean that weight-lifters and powerlifters do not experience type I fibre growth, but rather that growth of type I fibres is relatively less than for type II fibres. On the other hand, as seen previously in figures A and B, bodybuilders are successful in attaining growth in both type I and II fibres.

Collectively, muscle fibre data from competitive lifters indicate that the greatest difference between weightlifters or powerlifters and body builders is not whether muscle hypertrophy can occur, but rather that there is a preferential hypertrophy of certain fibre types. Obviously, these cellular adaptations must be related to competitive performance; muscular force and power for the weightlifters and powerlifters, and muscular size for the bodybuilders. It must also be noted that unlike the previous comparisons of intensity levels ranging from 40–95% 1RM, body builders spend considerable amounts of training time using loads ≥80% 1RM. As a result, examination of the muscle characteristics of athletes in hand, weightlifters and powerlifters train specifically these three lifting sports represents a much smaller range of relative training intensities. On the other hand, weightlifters and powerlifters train specifically to enhance 1RM capabilities, and thus routinely use loads approaching 100% 1RM. Another confounding factor, as previously mentioned, is the potential role of pharmaceutical contributions to these adaptations that cannot be determined from most of these studies. Further research would be necessary to determine the pharmaceutical mechanisms for differential adaptations based on resistance exercise intensity.

Intensity and Strength

Before we examine the skeletal muscle adaptations to varying loads, it is critical to remember that muscular strength (1RM) adaptations are dependent on the training load used. In other words, the largest increases in maximal strength occur with relatively heavier training loads. In making this statement, it must be noted that increases in maximal strength can occur from long-term training with a variety of relative resistance loads. But in general, to maximise the 1RM strength responses to a resistance exercise programme, one must handle relatively heavy loads. This illustration of the training specificity principle can be seen in figure 3. This bar graph clearly illustrates that the largest percentage increases in maximal strength occur with loads approaching maximal capacity (i.e. 100% 1RM), whereas lesser degrees of improvement occur with lighter loads. These responses are not due to different levels of effort since each training protocol involved maximal efforts for the conditions of each respective study. Obviously, an individual who is interested in maximal muscular strength cannot exclusively use maximal or near-maximal loads without the risk of overtraining. However, a critical amount of training time must be spent with these heavy loads if maximal strength is to be in-creased. The bottom line is that relatively heavy loads must be utilised if maximal strength is to be increased and/or maintained. It has been theorised that this axiom is even more important for those individuals who are advanced in terms of training experience and history.

Intensity and Hypertrophy

In order to extrapolate the relative (%) hyper-trophic responses to different relative training intensities, the mean percentage hypertrophy in-creases for a number of resistance exercise studies were determined from the reported data_. To more closely determine the intensity-specific training effect, the hypertrophic responses for each of the major fibre types (i.e. I and II, or I, IIA and IIB) was examined. How fibre type-specific relationships with relative intensity were determined is illustrated in the graphics left. The mean hypertrophic responses for type I and type II fibres is labelled in a scatterplot with the relative training intensity. As expected, the data are somewhat scattered, undoubtedly due to training factors other than relative intensity. Regardless, the regression line illustrates the ‘line of best fit’ for this relationship. For both fibre types, greater relative intensities were associated with greater hypertrophic

responses. It should be noted that 16 different training programmes were used to determine this relationship for type I fibres, while only eight were used for type II fibres. This is due to the fact that some studies separately reported the sub-types IIA and IIB.

Close examination of major fibre types reveal several important factors. First, the hypertrophy response for each fibre type is dependent only in part on the relative intensity. This is evident from the explained variances for type I (r² = 0.182), and type II (r² = 0.349) fibres. Thus, as expected, there are numerous other training-related variables that are contributing to the resulting muscle growth. Also apparent is the difference between the hypertrophic response for type I and II fibres. Greater relative growth is apparent for the type II fibres, which is in agreement with the training literature. Interestingly_, some of these findings are supported by the animal resistance exercise literature. The relative load (normalised for body mass) used for weight training exercise for cats explained a similar proportion of the variance (r² = 0.212) for hypertrophy of the palmaris longus muscle.

A study comparing the effect of high and low reps and sets on muscle growth . Mitchell et al 2012:

Subjects in the study trained their legs on the leg extension machine 3 times a week for 10 weeks, using one of three different set and rep configurations:

• 1 set of 10-12 reps (80% 1-RM) performed to voluntary failure (80%-1)

• 3 sets of 10-12 reps (80% 1-RM) performed to the point of fatigue (80%-3)

• 3 sets of 30-40 reps (30% 1-RM) performed to the point of fatigue (30%-3)

The figure left shows the change in the size of the quadriceps, measured using magnetic resonance imaging. As you can see, high reps and light weights (30%-3) stimulated just as much muscle growth as heavy weights and low reps (80%-3).

You could also incorporate a back-off set at the end of a series of heavy sets. Two or three heavy sets of 5-8 reps on the squat followed by a few lighter sets is one of the best ways to stimulate growth in your thighs.

The legs seem a lot more responsive to volume than the upper body, with an increased training volume shown to accelerate size and strength gains in the legs, but not in the upper body.

Conclusions

Several conclusions can be deduced from the preceding data. It appears that the muscular hypertrophy response to different relative training intensities follows a dose-response curve. In other words, the greater the %1RM, the greater the hypertrophy response. However, examination of the scatterplots of hypertrophic response of type I and II fibres, shown above, indicates that there may be a threshold for optimal growth responses. Once relative intensity reaches 80% 1RM, it appears that maximal growth is attained. Within the scope of the data available for this review, maximal growth occurs with loads between 80–95% 1RM. This, of course, spans a considerable repetition range that depends on the exercise being used.^[26,48] It is possible that this threshold is simply an artifact of so many of these studies using a relative intensity of approximately 80% 1RM. While some level of hypertrophy is possible at most relative intensities, an adequate load must be used to maximise this response. This concept of a load or intensity threshold for hypertrophy is also supported by animal data where it has been demonstrated that a critical load threshold (i.e. 30% of body mass) exists for weight-trained cats. Based on the data presented, figure 12 illustrates the optimal relative intensity range for muscular hypertrophy. The range of hypertrophy indicated for any one intensity represents the range of data from the included studies. As previously mentioned, at best, relative intensity ac-counts for only 18–35% of the hypertrophy r esponse, meaning that many other variables are likely to contribute to the observed growth responses. Nevertheless, relative intensity is likely to be one of the most important contributing training variables. The levels of hypertrophy for intensities >95% 1RM are theoretical and require further study to determine if the hypertrophy responses drops off as suggested if only using these extremely high relative intensities. However, the curve illustrated in figure above is supported by acute hormonal data for extreme levels of relative intensity. When sets of 100% 1RM loads have been used exclusively for a single training session, the responses of anabolic hormones are small or non-existent. Likewise, the acute anabolic hormonal responses for a training session performed at 40% 1RM loads is also minimal or non-existent. Although responses at the cellular or molecular levels were not monitored in either of these studies, these do provide evidence that an anabolic environment is unlikely if exclusively using these extreme intensities For those not wanting large levels of muscular hypertrophy (e.g. distance runners, athletes in weight class sports), it must be noted that one does not necessarily want to avoid all resistance exercise ≥80% 1RM. Rather, it is important to carefully titrate the volume of training performed at or above this intensity. It must be remembered that there are other physiological and performance reasons to train at these intensities besides muscular growth. In addition, the resistance training adaptations for many individuals/athletes may be already compromised by other components of the total training programme (e.g. aerobic conditioning). Therefore, inclusion of resistance training ≥80% 1RM may be necessary to counter the catabolic effects of other types of exercise.

What about exogenous hormones?

Most of our readers know of course that lots and lots of gymgoers use anabolic steroids, and as we recently posted many young clubbers also use AAS without training to obtain a muscular physique. We post some results from Shalender Bhasin et al that show that even guys that used AAS and didn’t train at all, build more muscle than guys that train their ass of and don’t take AAS. But.. Training and AAS is king. Then of course what we discussed here becomes relevant. How much and how heavy is your workload.

Bhasin et al 1996 randomly assigned 43 normal men to one of four groups:

1. placebo with no exercise,

2. testosterone with no exercise

3. placebo plus exercise

4. testosterone plus exercise

The men received injections of 600 mg of testosterone enanthate or placebo weekly for 10 weeks. The men in the exercise groups performed standardized weight-lifting exercises three times weekly.

Among the men in the no-exercise groups, those given testosterone had greater increases than those given placebo in muscle size in their arms mean change in triceps area (424 vs. -81 mm²), and legs (change in quadriceps area, 607 vs. -131 mm²; and greater increases in strength in the bench-press 9 vs. -1 kg, and squatting exercises (16 vs. 3 kg). The men assigned to testosterone and exercise had greater increases in fat-free mass (6.1 kg) and muscle size (triceps area, 501 mm²; quadriceps area, 1174 mm²) than those assigned to either no-exercise group, and greater increases in muscle strength (bench-press strength, 22 kg; squatting-exercise capacity, 38 kg) than either no-exercise group. Neither mood nor behavior was altered in any group. Conclusions: Supraphysiologic doses of testosterone, especially when combined with strength training, increase fat-free mass and muscle size and strength in normal men.

Training combined with AAS – Growth Hormone – Insulin etc would change the outcomes even more dramatically, if compared with natural athletes. Just think of today’s mass monsters.