Metabolic and hormonal responses to different resistance training systems in elderly men

Abstract

Objective: To compare acute and sub-acute responses in hormonal profile and metabolic parameters in elderly people who participated in two methods of strength training (ST) with equalized loads.

Methods and materials: A total of 12 elder individuals (65 ± 3 years) were randomly assigned to two training methods: constant intensity (CI, 3 sets of 10 repetitions with 75% of 1RM) and variable intensity (VI, 1st set: 12 repetitions at 67% of 1RM > 2nd set: 10 repetitions at 75% of 1RM and 3rd set: 8 repetitions at 80% of 1RM). Both methods included the following exercises: leg press, knee extension, and squat with 1 min rest intervals between sets. Free speed of execution and maximum range of movement were encouraged throughout each set for both protocols. Blood samples were analyzed included glucose, testosterone (T), cortisol (C), T/C rate, growth hormone (GH), and lactate at 2 and 24 h post intervention.

Results: There were no observed differences in glucose, testosterone, GH, and lactate concentrations both at 2 and 24 h after the execution of the two training methods. However, significant increases in the levels of T/C rate and decrease on cortisol were observed immediately post exercise for both protocols.

Conclusions: Although no significant differences were observed between the two interventions in relation to the hormonal and metabolic parameters analyzed, both training methods promoted a favorable response, with a slight superiority noted for the CI method relative to the hormonal profile.

Keywords:

• Strength training
• resistance training
• hormones
• pyramid
• testosterone

Introduction

The aging process leads to adverse modifications in the body structure, declines physical function, and ultimately increases the risk of disability and dependence. A number of these modifications occur in muscle-skeletal system such as changes in the size and in the proportion of different muscle fiber types, a reduction in bone mineral density and the presence of degenerative processes in the articulations. As consequence, some abilities are compromised, such as strength, power, balance, and flexibility.

Strength training (ST) is considered as one of the most popular recreational and professional physical activities. ST routines are performed by individuals interested in strength development for professional purposes, such as athletes, or by people who desire to be fit and healthy. The majority of these activities are performed in fitness centers and gymnasiums [1]. In addition, ST is also performed to improve health status and rehabilitation, and the benefits of ST are well documented in the scientific literature [2–4].

ST promotes significant changes in metabolic markers associated with muscular adaptations such as lactate, glucose, testosterone, cortisol, testosterone-cortisol ratio (T:C), and growth hormone (GH) [5–7]. These adaptations can be considered important in the monitoring and evaluation of the training programs success [8].

T:C has been used as a hormonal marker related to anabolic-catabolic body homeostasis [9], however, it is not clear how T:C responds to different training methods. Only a few studies to date have investigated the effects of varied ST workloads (volume and intensity) on T:C. It is well known that a variety of different training systems are able to promote musculoskeletal adaptations [10]. However, when ST is carried out using the same program for an extended time period, the adaptive response plateaus, which motivates individuals to consider alternative training methods [11,12].

Despite evidence that variability of stimuli is needed to promote steady neuromuscular adaptations, the characterization of hormonal responses, in particular that of T:C, to various ST methods is still relatively unexplored in the scientific literature, especially in relation to elderly populations. Two ST methods, the multiple-set of constant intensity (CI) and the multiple-set of variable intensity (VI), also named ascending pyramid [13], are often used for the purpose of enhancing muscular fitness. However, to the authors’ knowledge, acute and sub-acute hormonal responses using these methods in elderly people with previous experience in ST is lacking. Thus, the objective of this study was to compare the hormonal, acute, and sub-acute metabolic responses derived from elderly individuals who participated in CI versus VI with equalized loads.

Materials and methods

Experimental approach to the problem

This study assessed the metabolic and hormonal response in previously trained elderly men carried out in two different, but equalized, ST systems. All participants were given two experimental sessions with 5 d of recovery afforded after the last session. Both protocols included the same exercises. For the CI protocol, all participants performed 3 sets of 10 repetitions with 75% of 1RM and for the IV protocol, the volunteers performed 3 sets of 12 repetitions with 67%-1RM; 10 repetitions with 75%-1RM, and 8 repetitions with 80%-1RM with 1 min rest interval in all sets.

Subjects

Following approval from the Committee on Ethics in Research of São Judas Tadeu University (n° 2.044.487/2017) and the completion of the relevant informed consent forms, 12 elderly men with previous experience in ST, but inactive between 6 months and one year, volunteered to participate in the study (see Table 1). Individuals with a known history of cardio metabolic disease, muscle injury (in the last 12 months), continuous, or interrupted use of medication or dietary supplementation for up to six months or more, were excluded from the study.

Table 1. Characterization of the sample.

Parameters	Mean ± SD
Age (years)	65 ± 3
Body mass (kg)	86 ± 18
Height (m)	1.75 ± 0.07
BMI (kg/m^2)	28 ± 4

Values expressed as the average ± standard deviation from average.

BMI: body mass index

Anthropometric assessments

Body composition and anthropometric parameters were assessed following the parameters used in a previous study of our group [14,15]. Body mass was determined using a calibrated Toledo digital scale (Model 2096PP/2) (Toledo^®, São Paulo, Brazil). Stature was measured with a SANNY stadiometer (model ES2030) (Sanny, São Bernardo do Campo, Brazil). Body mass index (BMI) for all subjects was calculated using the values obtained.

Assessment of maximum dynamic strength

To establish the intensity used for both training protocols it was necessary to determine the 1 repetition maximum (1RM) values for all exercises used in the training program. Prior to the first session, all participants were submitted to 1RM tests for the following exercises: leg press, knee extension, and squat. All tests were conducted at the same time of day in an attempt to control the influence of diurnal variation (morning testing) as described in the previous publication from our group [16].

One session of testing was considered adequate for the determination of 1RM as all subjects were familiar with the exercises and all had knowledge of their own individual maximal effort. Prior to the 1RM test, all participants were asked to refrain from exercise for 72 h before testing. The test was conducted in accordance with the guidelines established by the National Strength and Conditioning Association [17]. Briefly, the test involved a series of warm-ups, with 20 repetitions, followed by adequate increases in load until individual subjects reached 1RM without undue fatigue. A research assistant determined the success or failure of each 1RM test.

Determination of the plasmatic levels of testosterone, cortisol, growth hormone (GH), lactate, and glucose

Specific kits were used to determine the plasmatic concentrations of cortisol, testosterone and GH (DSL-10–2000, Diagnostic Systems Laboratories^©, Webster, TX). Lactate and glucose levels were obtained using the Accutrend Plus^® (Brasil). Blood samples were collected before and after 2 and 24 h post exercise. At each time point 30 mL of blood was collected: 20 mL in a tube with fluoridated EDTA and 10 mL in a dry tube. Following collection, the blood was stored under controlled refrigeration at 4 °C, and was then centrifuged and frozen at −20 °C [8,18].

Perceived exertion and training load

All subjects reported their rating of perceived exertion CR-10 scale conform previously publication [19]. Additionally, in both experimental session (CI or VI) the internal training load was calculated by multiplying of total of repetitions and perceived exertion. The total load was evaluated by following equation: Set (n°) × repetitions (n°) × intensity (kg) × exercise (n°).

Procedures

The two experimental single sessions were performed by each subject in a randomized order. The first session was conducted 72 h after determining the load to be used in the experimental session (CI or VI), both with equalized loads. Additionally, the experimental session interval was repeated 5 d after the last session was conducted. Both protocols included the following exercises: leg press, knee extension, and squat. During the CI protocol all participants performed 3 sets of 10 repetitions with 75% of 1RM in each exercise. During the IV protocol, the volunteers performed 3 sets of each exercise, in the following order: (1) 12 repetitions with 67%-1RM; (2) 10 repetitions with 75%-1RM; and (3) 8 repetitions with 80%-1RM. Free speed of execution and maximum range of movement were encouraged throughout each set for both protocols. A 1 min rest interval was afforded between all sets.

Statistical analysis

A Shapiro–Wilks test was applied to verify the normality of the data. When normality was confirmed, and to compare the different exercise phases, a two-way ANOVA test and Tukey’s post hoc for repeated measures was used. Significance level was 5% (p ≤ .05) and the results were presented as the average ± standard error. The effect size (d) was calculated. Statistical tests were carried out using a statistical test package, software Graph Pad Prism version 4.0 (GraphPad Software, San Diego, CA).

Results

No differences (p < .05) were found on perceived exertion (CI: 7.6 ± 0.8, VI: 7.8 ± 0.6), internal load (CI: 683 ± 71, VI: 705 ± 52; UA.) and total load (CI: 10800 ± 750, VI: 12370 ± 860; UA.) demonstrating the similar load on both systems.

No differences were observed in concentrations of glucose, testosterone, GH, and lactate 2 and 24 h after both interventions as shown in Table 2.

Table 2. Metabolic and hormonal parameters before 2 and 24 h post execution of variable and constant intensity protocols.

Parameters	CI			VI
	Before	2 h	24 h	Before	2 h	24 h
Glucose (m/dL)	99.4 ± 4.2 (0.04)	103.1 ± 4.7 (0.04)	100.4 ± 4.8 (0.04)	100.1 ± 2.1 (0.02)	102.1 ± 3.5 (0.03)	99.2 ± 2.4 (0.02)
Testosterone (ng/dL)	36.0 ± 12.5 (0.34)	48.4 ± 9.3 (0.19)	34.4 ± 14.1 (0.40)	37.4 ± 13.1 (0.35)	47.7 ± 9.1 (0.19)	35.4 ± 13.3 (0.37)
Cortisol (ug/dL)	6.7 ± 3.1 (0.46)	6.4 ± 4.8* (0.75)	7.1 ± 2.3 (0.32)	6.4 ± 4.3 (0.67)	6.1 ± 3.1* (0.50)	5.4 ± 2.7 (0.50)
T:C	5.3 ± 6.2 (1.16)	7.8 ± 3.4* (0.43)	4.8 ± 7.1 (1.47)	5.7 ± 7.1 (1.24)	7.7 ± 3.1* (0.40)	6.4 ± 2.7 (0.42)
GH (ng/mL)	0.89 ± 2.2 (2.47)	0.70 ± 3.1 (4.42)	0.80 ± 1.3 (1.62)	0.99 ± 2.2 (2.22)	0.85 ± 5.1 (6.00)	0.87 ± 1.9 (2.18)
Lactate (mMol/L)	0.9 ± 0.8 (0.88)	1.26 ± 2.34 (1.85)	1.1 ± 1.2 (1.09)	1.1 ± 0.7 (6.36)	1.46 ± 1.67 (1.14)	1.0 ± 0.9 (9.00)

Values expressed as the average ± standard deviation and (coefficients of variation) of the hormonal and metabolic parameters pre 2 and 24 h post performing ST systems with constant intensity (CI) and varied intensity (VI).

*p < .01 versus before.

However, there was a significant decrease in cortisol and increase in T:C after 2 h using both training methods. After 24 h, no differences were observed between the interventions. Additionally, no significant alterations were observed in the effect size classifications irrespective of the training protocol used in all parameters (Table 3).

Table 3. Effect size related to rest.

Parameters	CI		VI
	Cohen’s d		Cohen’s d
	2 h	24 h	2 h	24 h
Glucose (m/dL)	0.88 (large)	0.23 (medium)	0.95 (large)	0.42 (medium)
Testosterone (ng/dL)	0.99 (large)	0.12 (small)	0.78 (medium)	0.15 (small)
Cortisol (ug/dL)	0.41 (small)	0.12 (small)	0.06 (small)	0.16 (small)
T:C	0.40 (small)	0.22 (medium)	0.28 (medium)	0.09 (small)
GH (ng/mL)	−0.08 (small)	0.04 (small)	0.06 (small)	0.05 (small)
Lactate (mmMol)	0.45 (small)	0.33 (medium)	0.51 (medium)	0.14 (small)

Discussion

To the authors’ knowledge, no studies to date have compared the acute and sub-acute physiological responses to CI and VI in elderly populations. The VI method, also known as ascending pyramid, is popular for its inherent intra-workout changes in training stimuli as opposed to a conventional ST format [10]. The hypothesis for this method is that progressively increasing the load across sets elevates the magnitude of physiological stress, thereby maximizing exercise-induced metabolic and hormonal responses. Charro et al. [20] showed that VI produced significant changes in blood lactate, cortisol, T:C and GH, without alterations in testosterone and blood glucose. The study used similar protocols to those employed in this study except for the fact that the subjects were young adults. In this study, both methods (CI and VI) resulted in significant elevations in cortisol and T:C, without alterations in glucose, testosterone, and GH concentrations. A follow-up study by the same lab [13] assessed changes in indirect markers of muscular injury after traditional and pyramidal exercise protocols and found similar responses in the inflammatory markers (creatine kinase, myoglobin, and C-reactive protein) for both methods. These findings provide evidence that the VI system seems to confer no additional benefits compared to a traditional training protocol with respect to the acute physiological response to ST.

Some studies [21,22] suggest that the different metabolic and hormonal responses to ST are associated with a greater range of variation, such as the loads used (example: 30% versus 80%-1R) and the number of repetitions performed (example 8–12 versus >25RM). In this study and others investigating the acute systemic effects of pyramid versus traditional ST systems [13,20] the range of variation of loads and repetitions was small, which may help explain the absence of difference between the interventions. It is worth mentioning that although the results from this study did not observe significant differences between protocols, the effect size revealed a greater magnitude of response for the CI system in the relation T:C ratio, 2 h post training session. The implications of these findings are not clear but warrant further study in an elderly population.

From a practical standpoint, controversy exists as to the impact of the acute systemic response on muscular adaptations. Several studies have shown a positive correlation between post-exercise hormonal elevations and skeletal muscle hypertrophy [23–26] while others have failed to show significant associations between these variables [27–30]. A recent review [12] on the topic concluded that if a relationship does in fact exist between exercise-induced systemic alterations and muscle growth, the overall magnitude of the effect would be at best modest. However, the body of literature on the topic is specific to the effects in young individuals. The extent to which this physiological response impacts elderly individuals as studied herein remains to be determined.

This, as well as previous studies, support the conclusion that CI and VI methods are effective training programs for inducing hormonal and metabolic responses after ST in elderly. CI and VI methods can elicit a significant increase on T:C in this population with a similar training load. Additionally, strength and conditioning professionals can use CI and VI methods to optimize the post-workout response to a ST session. It should be emphasized that the variation of methods can be an interesting strategy to keep elderly subjects motivated, avoiding monotony and promoting adherence to the training program.

Conclusion

Although this study did not find significant differences between conditions in the metabolic and hormonal parameters assessed, both CI and VI provided a favorable response to ST adaptation in elderly people. The practical implications of these findings warrant further study.

Acknowledgments

The authors thank CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) fellowships addressed to Paunksnis MR. The fund providers had no role in decision to publish and preparation of the article.

Disclosure statement

• No potential conflict of interest was reported by the authors.