Strength exercise is a strategy applied in sports and physical training processes. It may induce skeletal muscle hypertrophy. The hypertrophy is dependent on the eccentric muscle actions and on the inflammatory response. Here, we evaluate the physiological, immunological, and inflammatory responses induced by a session of strength training with a focus on predominance of the eccentric muscle actions. Twenty volunteers were separated into two groups: the untrained group (UTG) and the trained group (TG). Both groups hold 4 sets of leg press, knee extensor, and leg curl at 65% of personal one-repetition maximum (1RM), 90 s of recovery, and 2
Regular physical exercise has achieved wide acceptance by the overall population, professional organizations, and the medical community. Many important international communities—such as UNESCO and ACSM—have been stimulating the inclusion of regular physical exercise for the population around the world. Nowadays, there is a strong body of scientific evidences for prescribing physical exercise as a prevention and therapy in many different chronic diseases. This amount of information suggests that physical exercise is able to work as a therapy on these disease pathogenesis and symptoms, and the interpretation of these scientific literatures can also indicate the optimal type and dose for prescription of physical exercise [
The protocols of strength training exercises are an essential part of various training processes, such as in health maintenance, in recreational practitioners, and in the improvement of professional sports performance [
The strength training has been related to the induction of skeletal muscle hypertrophy according to the following parameters: load components around 60–85% of the values obtained in maximum strength test (1RM (one repetition maximum)), three to six series, six to twelve repetitions, and pauses between sets of one to three minutes [
Since there is a close relation between exercises with the systemic and local inflammatory response [
There is a body of evidence showing that many types of exercise protocols can modulate the plasma level of myokines, which are cytokines produced in the skeletal muscle tissue. The entire “secretome” of exercising skeletal muscle has not yet been described. Here, we investigated some myokines such as apelin, brain-derived neurotrophic factor (BDNF), fatty acid-binding proteins-3 (FABP3), follistatin-like-1 (FLST1), osteonectin, and interleukin-15 (IL-15). Apelin is important in increasing the strength of cardiac contraction [
In this sense, the aim of this study was to investigate the effects of single strength training sessions on physiological (HR, RPE, VAS, and lactate), immunological (leukocyte number), and skeletal muscle mediators, for example, myokines, apelin, BDNF, FABP3, FLST1, osteonectin, and IL-15, in trained (TG) and untrained (UTG) subjects.
Twenty young male volunteers ranging from 18 to 35 years old were separated into two groups: an untrained group (UTG), weight of 74.8 ± 14.2 (kg) and a trained group (TG) consisting of trained practitioners, weight of 72.2 ± 3.8 (kg), that had been practicing strength training for at least 6 months continuously. The inclusion criteria for both groups were the absence of musculoskeletal lesions in the last six months in the lower limbs, spine, and pelvis; no smoking; no drinking of alcohol for at least 3 days prior to the study. The exclusion criteria for the volunteers were absence on the test day, any disease and/or clinial condition that compromises the performance, or any use of anabolic hormones or supplements. Ethical clearance for this study was obtained from the Ethical Committee of the Federal University of Ouro Preto, MG (Res. 196/96 - CAAE 56307716.2.0000.5150).
The volunteers performed a strength training session according to the load regulations for skeletal muscle hypertrophy. Immediately before, immediately after, and 2 hours after the training session, blood samples were collected from the radial vein to quantify physiological markers, leukocytes, and myokines. All procedures were performed in the Laboratory of Inflammation and Exercise Immunology (LABIIEX/CEDUFOP) from Ouro Preto University (UFOP), Ouro Preto, Brazil.
Each volunteer came to the laboratory for a total of three times. On the first day, the volunteers were submitted to a physical examination which determined their body composition (body fat), weight, height, and circumference of the thigh and calf, as well as determining the range of motion of the knee joint. On the second trial day, the volunteers performed the one-repetition maximum test (1RM), and on the third trial day—respecting a minimum interval of one week (7 days)—the volunteers performed a single strength training session in a leg press, knee extensor, and leg curl. First, the volunteers warmed up in a cycle ergometer for 5 minutes in a low intensity. After that, both groups (UTG and TG) performed 4 sets of leg press, knee extensor, and leg curl exercises in this sequence. The overload was adjusted at 65% of personal one-repetition maximum (1RM) for each machine. The time of recovery was 90 s, and the duration of muscle tension was 2 seconds for concentric action and 3 seconds for eccentric action in each repetition. The volunteers performed between 8 and 10 repetitions for each exercise. All training sessions spent around 35–40 minutes. The volunteers were oriented not to perform any physical exercise at least for 3 days. After the training session, peripheral blood was collected immediately before, immediately after, 2 hours after, and 24 hours after the end of exercise. Blood samples were collected from the median cubital vein by a professional nurse. The collected blood was taken to the Immunobiology of Inflammation Laboratory (LABIIN), Clinical Analysis Laboratory (LAPAC), and Interdisciplinary Laboratory of Medical Investigation (LIIM) to be analyzed. The blood samples were taken from the median cubital vein in the forearm using two different types of tube: an S-Monovette® tube 2.7 ml, EDTA K3, was used for hemogram analyses, and an S-Monovette 7.5 ml Serum tube that does not contain any anticoagulant was used for plasma separation for protein analyses. The blood was transported using standard conditions for transport of biological materials. The time spent to transport the blood samples was around 10 minutes in appropriate conditions in a cooler box with ice.
Heart rate was assessed by using a personal POLAR tool, and the values were recorded during the all-strength training session. After each set of exercise for every session, the volunteers noted their rate of perceived exertion using the Borg scale [
The lactate level for peripheral blood circulation was analyzed by using Accutrend Plus (Roche) before, immediately after, and 2 hours after the end of the strength training session.
To prevent volunteers from suffering from dehydration, fatigue, and sudden drop of glucose, they were fed within 30 minutes of posttraining. The meal was based on the mean age of the groups (25.5 years) and weight (73.45 kg), using the FAO/WHO formula (1985) for energy determination (15.3 × P + 679), plus 30% of the total value, since the activity was preformed until exhaustion. The average daily caloric recommendation for volunteers was 2.343 kcal/day, with 20% dedicated to the posttraining meal. The diet followed the recommendation of the Brazilian Society of Sports Medicine (2009) and focused on the supply of complex carbohydrates (about 70% of the total amount of calories offered), since it plays a crucial role in energy supply and—after the effort carbohydrate intake—aims to restore depleted glycogen stores, to guarantee anabolic standard, and to reduce protein degradation [
Full blood counts were performed using a five-part differential hematology analyzer (Beckman Coulter AcT 5diff AL Hematology Analyzer, California, USA). The hematology analyzer uses a sequential dilution system and dual-focused flow fluid dynamic technologies employing the Coulter principle of impedance to count and size the cells.
In this study, a HMYOMAG-56K MILLIPLEX® MAP Human Myokine Magnetic Bead Panel and Luminex® were used for analysis of myokines following the manufacturer’s protocols. In this study, the human myokines analyzed were apelin, brain-derived neurotrophic factor (BDNF), fatty acid-binding proteins-3 (FABP3), follistatin-like-1 (FLST1), osteonectin, and interleukin-15 (IL-15).
Initially, characterization traits (weight, height, percentage of body fat, and age) of both groups (TG and UTG) were compared with
The volunteers’ weight was 74.8 ± 14.2 (kg) in UTG, while in TG it was 72.2 ± 3.8 (kg). The mean of height in UTG was 175.1 ± 8.4 (cm) and, in TG, 173.5 ± 7.7 (cm), while the percentage of body fat (% BF) was 15.0 ± 8.7 and 9.8 ± 2.9 in UTG and TG, respectively. The mean of age (years) of the volunteers in UTG was 24.5 ± 2.8 and in TG 26.6 ± 1.3. There was no difference (
List of foods offered and their macronutrient values.
Food | Amount | Caloric value | Protein | Carbohydrate | Total fat |
---|---|---|---|---|---|
Grape juice | 200 g | 123 kcal | 0.6 g | 30.2 g | 0 g |
Orange | 90 g | 42.3 kcal | 0.8 g | 10.5 g | 0.1 g |
Low-fat yogurt | 70 g | 39.2 kcal | 4.0 g | 5.3 g | 0.1 g |
Granola | 20 g | 77.6 kcal | 1.9 g | 14.7 g | 1.2 g |
Whole bread | 44 g | 110 kcal | 4.1 g | 20.6 g | 0 g |
Turkey breast | 32 g | 44.8 kcal | 9.6 g | 0 g | 0.3 g |
Ricotta | 20 g | 34.8 kcal | 2.2 g | 0.6 g | 2.6 g |
Lettuce | 10 g | 1.3 kcal | 0.1 g | 0.2 g | 0 g |
Tomato | 30 g | 6.1 kcal | 0.2 g | 1.5 g | 0 g |
Total | 511 g | 459 kcal | 23.2 g (20.6%) | 80.2 g (71%) | 4.1 g (8.3%) |
Table
The characterization of the volunteers. This table shows the absolute values and means of each volunteer for weight (kg), height (cm), percentage of body fat (% BF), and age (years) (
Volunteers | Weight (kg) | Height (cm) | % BF | Age | BMI |
---|---|---|---|---|---|
Untrained (UTG) | |||||
V1G1 | 60.7 | 164 | 16.7 | 30 | 22.5 |
V2G1 | 82.5 | 168 | 30.5 | 25 | 29.2 |
V3G1 | 63.5 | 187 | 4.5 | 22 | 18.1 |
V4G1 | 68.6 | 179 | 8.2 | 27 | 21.4 |
V5G1 | 55.8 | 168 | 4.4 | 22 | 19.7 |
V6G1 | 66.8 | 167 | 5.5 | 21 | 23.8 |
V7G1 | 83 | 185 | 15.2 | 25 | 24.2 |
V8G1 | 85.4 | 177 | 22.8 | 27 | 27.1 |
V9G1 | 75.5 | 169 | 16.9 | 21 | 26.4 |
V10G1 | 106 | 186 | 24.6 | 25 | 30.7 |
Mean | 74.8 | 175.1 | 15.0 | 24.5 | 24.3 |
SD | 14.2 | 8.4 | 8.7 | 2.8 | 3.8 |
Trained (TG) | |||||
V1G2 | 70 | 167 | 13 | 27 | 25.1 |
V2G2 | 74.4 | 181 | 7.7 | 24 | 22.7 |
V3G2 | 74.7 | 162 | 13.3 | 26 | 28.4 |
V4G2 | 77.4 | 180 | 6.3 | 29 | 23.8 |
V5G2 | 70.4 | 170 | 7.2 | 28 | 24.3 |
V6G2 | 68 | 174 | 6.9 | 26 | 22.4 |
V7G2 | 66 | 162 | 12 | 27 | 25.1 |
V8G2 | 77.8 | 186 | 10 | 26 | 22.4 |
V9G2 | 69.2 | 175 | 7.6 | 26 | 22.6 |
V10G2 | 74.4 | 178 | 14.1 | 27 | 23.4 |
Mean | 72.2 | 173 | 9.8 | 26.6 | 24.1 |
SD | 3.8 | 7.7 | 2.9 | 1.3 | 1.8 |
After the single strength training protocol session, the heart rate increased from 71.8 ± 10.4 to 140.2 ± 8.2 bpm/min (
The strength training exercise protocol alters physiological markers. The single strength training protocol session elevated the heart rate in UTG and TG. The RPE and VAS were also elevated in both groups. The lactate levels were elevated differently when comparing UTG and TG. The CK level increased at 2 h and at 24 hours in UTG and in TG only 24 hours after the end of exercise. Data are presented in mean and standard errors, and the level of significance is
The strength training exercise protocol increased the number of white blood cells from 6.9 ± 0.9 (103/
The strength training exercise protocol alters the number of subpopulation in the white blood cells (leukocytes). The red lines mean the reference value. The single session of exercise was able to elevate the number of white blood cells immediately and 2 hours in UTG and TG (Figure
The plasma lactate level positive correlated with the total number of leukocytes (Figure
The plasma level of lactate was positively correlated with the increase in the number of leukocytes. There was a relationship between the plasma lactate level and the number of total leukocytes (Figure
The strength exercise protocol was able to change the levels of important myokines. The plasmatic apelin levels increased in UTG (Figure
The single strength training exercise protocol induces alterations in the level of circulating myokines. The single session of exercise was able to elevate the level of some myokines IL-6 in TG 2 hours (Figure
There are some noteworthy findings from this study: (i) the single strength training session was able to induce physiological stress, (ii) the local skeletal muscle contraction (lower members) was able to change the leukocyte counting in the peripheral blood, and finally (iii) the single strength training session is an enough stimuli to produce and release myokines (apelin, BDNF, FABP3, and FLTS1) in the peripheral blood circulation.
The monitoring of the physiological workload in this protocol was guaranteed by the necessity of stimuli modifying the body homeostasis. The strength training exercise protocol was able to change physiological parameters such as heart rate (HR), rate of perceived exertion (RPE), and visual analog scale (VAS). In addition, this strength exercise protocol also increased the level of lactate (immediately after) and creatine kinase (2 and 24 hours) in the blood circulation from the volunteers. The interesting result here is that the level of increase in lactate levels immediately after the end of exercise was different when comparing UTG and TG. TG appears to produce less lactate or may remove it faster than does UTG from the circulation. The possible explanation for this perception could be the increase in key enzyme activities induced by the training process, such as enzymes of glycolysis, such as glycogen phosphorylase, phosphofructokinase (PFK), and lactate dehydrogenase (LDH) [
Over the past two decades, a variety of studies has demonstrated that exercise induces considerable physiological change in the immune system. Acute and chronic exercise alters the number and function of circulating cells of the innate immune system (e.g., neutrophils, monocytes, and natural killer (NK) cells) [
However, there is less information about the effects of the strength training protocol on the response of number of white blood cells and in the levels of myokines. The analyses of results show that the single session of strength training for lower members can elevate the total number of white blood cells. In UTG, the number of white blood cells was increased immediately after, had a further increase 2 hours after the end of exercise, and then returned to basal levels 24 hours after the end of the session. In UTG, the number of white blood cells was equally higher immediately and 2 hours after the end of exercise (Figure
Interestingly, the plasma level of lactate was positively correlated with the increase in the number of total leukocytes, neutrophils, and monocytes immediately after exercise and with leukocytes and neutrophils 2 hours after the end of the session (Figure
This process seems to produce some of the symptoms associated with muscle injury, including the loss of muscle function, delayed onset muscle soreness (DOMS), and an increase in muscle proteins in circulation representing damage to the plasma membrane [
Studies involving systemic inflammatory responses following exercise protocols have demonstrated a variety of responses, such as the type of exercise, the amount of muscle tissue recruited, the status (aerobic or anaerobic), the type of muscle action (concentric or eccentric), and lastly, the duration and intensity which define the magnitude of local and systemic inflammation [
Cytokines are responsible for the coordination, amplification, and regulation of the magnitude and duration of inflammatory events and their effects [
Variations in inflammatory responses of strength exercises are related to the duration, intensity, and other physiological factors related to stress, such as body temperature, endocrine response, metabolic acidosis, oxidative stress, and muscle damage caused by the exercise session [
The finding that the muscle secretome, which is an endocrine organ, consists of several hundred secreted peptides provides a conceptual basis and a whole new paradigm for understanding how muscles communicate with other organs, such as the adipose tissue, the liver, the pancreas, the bones, and the brain [
The basal plasma of UTG and TG volunteers shows different levels of apelin (Figure
Apelin is important in increasing the strength of cardiac contraction [
The fatty acid-binding proteins-3 (FABP3) is a small cytoplasmic protein released from cardiac myocytes following an ischemic episode. These molecules are involved in active fatty acid metabolism, where it transports fatty acids from the cell membrane to mitochondria for oxidation. A single session of strength exercise was able to elevate the plasma level of these molecules in both groups immediately after and 2 h after the end of exercise (Figure
Follistatin-like-1 (FLST1) is a cytokine with diverse actions in the maintenance of cardiac homeostasis and remodeling. Follistatin-like-1 (Fstl1) is a secreted glycoprotein expressed in the adult heart and is induced in response to injurious conditions that promote myocardial hypertrophy and heart failure [
Together, these results show that the strength training session is enough stimuli to change physiological parameters such as HR, RPE, VAS, and lactate levels. This exercise protocol also induces changes in the counting of white blood cells, especially neutrophils, lymphocytes, and monocytes. In addition, a single session of strength training can modulate some important myokines such as Apelin, FABP3, and FLST1.
According to these results, a single session of strength exercise protocol could change the physiological and immunological parameters and stimulate the production and release of important myokines. The acute strength training session induces the elevation of the heart rate, RPE, VAS, lactate, and CK. This protocol also changed the number of white blood cells (neutrophils, lymphocytes, and monocytes) and myokines such as IL-6, BDNF, and FABP3 myokines. In this sense, the strength training session is able to modulate some aspects of immune systems.
There is a straight relationship between exercise and the immune system. Exercise may modulate the immune system response acutely and chronically. Nevertheless, physical exercise also induces the release of myokines in the blood circulation. The physiological function of myokines produced by the skeletal muscle is to protect and improve the functionality of many organs. Furthermore, there is convincing evidence that factors secreted by the skeletal muscle act as endocrine signaling mediators and are involved in the beneficial effects of exercise on almost all cell types and organs. From now on, it is important to discover the role of these molecules in the systems and the organs of the body and investigate the difference between physical exercise protocols in the levels of these myokines.
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that there is no conflict of interest regarding the publication of this article.
The authors would like to thank the Pilot Laboratory and Clinical Analysis (LAPAC/UFOP). They would also like to especially thank Érica Leandro Marciano Vieira and the Interdisciplinary Laboratory of Medical Investigation (LIST) for all the support in the myokine analysis. André Talvani was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico with the Fellowship of Research Productivity.