continuous moderate-intensity but not high- intensity

CONTINUOUS MODERATE-INTENSITY BUT NOT HIGHINTENSITY INTERVAL TRAINING IMPROVES IMMUNE FUNCTION BIOMARKERS IN HEALTHY YOUNG MEN MARWA KHAMMASSI,1,2,3 NEJMEDDINE OUERGHI,1,3 MOHAMED SAID,1 MONCEF FEKI,4 YOSRA KHAMMASSI,1 BRUNO PEREIRA,5 DAVID THIVEL,2 AND ANISSA BOUASSIDA1 1 Downloaded from https://journals.lww.com/nsca-jscr by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3Eq7LPcN6/vApyt9RoQIbexcMhJSrfZbPQqOTWKpG82w= on 01/08/2019

Research Unit, Sportive Performance and Physical Rehabilitation, High Institute of Sports and Physical Education of Kef, University of Jendouba, Kef, Tunisia; 2EA 3533, Laboratory of the Metabolic Adaptations to Exercise Under Physiological and Pathological Conditions (AME2P), Clermont University, Blaise Pascal University, Aubie`re, Cedex, France; 3Faculty of Science of Bizerte, University of Carthage, Bizerte, Tunisia; 4LR99ES11, Laboratory of Biochemistry, Rabta Hospital, Faculty of Medicine of Tunis, Tunis El Manar University, Tunis, Tunisia; and 5Biostatistics Unit (DRCI), Clermont-Ferrand University Hospital, Clermont-Ferrand, France ABSTRACT

INTRODUCTION

Khammassi, M, Ouerghi, N, Said, M, Feki, M, Khammassi, Y, Pereira, B, Thivel, D, and Bouassida, A. Continuous moderateintensity but not high-intensity interval training improves immune function biomarkers in healthy young men. J Strength Cond Res XX (X): 000–000, 2018—Effects of endurance running methods on hematological profile are still poorly known. This study aimed to compare the effects of 2 training regimes; high-intensity interval training (HIIT) and moderate-intensity continuous training (MCT) performed at the same external load on hematological biomarkers in active young men. Sixteen men aged 18–20 years were randomly assigned to HIIT or MCT group. Aerobic capacity and hematological biomarkers were assessed before and after 9 weeks of interventions. At baseline, aerobic and hematological parameters were similar for the 2 groups. After intervention, no significant change was observed in maximal aerobic velocity and estimated _ O2max in both groups. Leukocyte (p , 0.01), lymphocyte (p , V 0.05), neutrophil (p , 0.05), and monocyte (p , 0.01) count showed significant improvements in response to the MCT compared with the HIIT intervention. The MCT intervention favored an increase in the number of immune cells, whereas the opposite occurred as a result of the HIIT intervention. These findings suggest that MCT interventions might be superior to HIIT regimes in improving immune function in active young men.

KEY WORDS continuous training, external load, hematological biomarkers, young men

Address correspondence to Dr. Marwa Khammassi, khammassimarwa. [email protected]. 00(00)/1–8 Journal of Strength and Conditioning Research 2018 National Strength and Conditioning Association

E

ndurance training leads to many physiological changes and favors a better transport of the oxygen from the atmosphere to the mitochondria, and thus boosts performance (20). Continuousand interval-running modalities are the most common methods for endurance training (51). Each modality mainly relies on specific durations and intensities being then differentially used depending on the exact training targets (54). Continuous training consists of aerobic exercise bouts performed at low to moderate intensity without rest intervals (16), whereas interval training consists of alternating highintensity periods of work with active or passive rest periods (38,39). The comparison between both training modalities has been widely discussed, and their effects on physiological and metabolic parameters questioned and compared (4,6,23). With a particular focus on aerobic capacity, this comparison revealed fluctuating results, with some authors reporting similar effects between the 2 training methods (50,51,53), some favoring continuous training and others favoring intermittent training (6,12,15). However, it seems to be unanimous that both modalities (intermittent or continuous) might affect the hematological profiles of healthy individuals. This would essentially result from the improvement of individuals’ oxygen transport capacity in the blood, which was mainly determined by the hemoglobin concentration, the number of circulating erythrocytes, and the efficiency of their functions (49). Improvements in aerobic capacities and performances also depend on other central factors such as maximal cardiac output, pulmonary diffusion, and blood volume and flow (2). Among the changes that occur in blood profile in response to physical training, the alteration of humoral and cellular immune response has been well documented in the available literature. In addition, it has been shown that the immune response essentially depends on the exercise characteristics VOLUME 00 | NUMBER 00 | MONTH 2018 |

Copyright ª 2018 National Strength and Conditioning Association

1

Hematological Responses to Physical Training (43). Indeed, several studies have shown that moderate training boosts immune functions, whereas intense training programs reduce it (10,41). Specifically, Nieman et al. (35) noted that moderate exercise training was associated with elevated natural killer (NK) cell activity and reduced upper respiratory infections symptomatology. By contrast, Gleeson et al. (11) showed that 7 months of intensive training suppressed both systemic (significant reduction in the absolute number and percentage of NK cells) and mucosal immunity (significant suppression of serum immunoglobulin (Ig)A, IgG, and IgM, and salivary IgA concentration), which could increase the susceptibility for infections. Although previous studies have investigated the hematological changes in response to endurance training (14,21,45), none to our knowledge have directly compared the effect of short-duration highintensity interval training (HIIT) vs. moderate-intensity continuous training (MCT) on the hematological profile of healthy, active young men. Moreover, the few available studies that have compared intermittent and continuous training have not used training of similar workloads. Therefore, the aim of this pilot study was to compare the effects of 2 aerobic training modalities (HIIT vs. MCT) of identical workload (matched duration) on aerobic capacities and hematological profile in active young men.

METHODS Experimental Approach to the Problem

The study was conducted from September 2013 to November 2013. All participants attended a medical and inclusion visit realized by a physician to ensure their ability to complete the whole study. The participants were then randomly allocated to either a MCT or HIIT group and assessed on measures of aerobic capacity and hematological profile at baseline and after 9 weeks of each training program (MCT and HIIT). Subjects

This study was performed on 16 healthy active male volunteers aged 18–20 years (mean age as 6 SD: 18.9 6 1.0 years), without any history of hematological diseases. Participant characteristics are displayed in Table 1. The study was conducted according to the Declaration of Helsinki, and the protocol was fully approved by the Scientific and Ethical Committee of High Institute of Sports and Physical Education of Kef. The study was also approved by the local committee of the University that depends on the Ethics Committee of High Institute of Sports and Physical Education of Kef, on behalf of the National Ethics Committee. Accordingly, the participants received a complete verbal description of the protocol, an outline of the potential risks, and benefits of participation, and if happy, the participants were asked to sign an informed consent form accordingly. Once enrolled, the participants were then randomly divided into 2 experimental groups: (a) HIIT program (HIIT group, n = 8); (b) MCT program (MCT group, n = 8). All participants were nonsmokers, nonalcoholic drinkers, and without any history of illness. Participants were

2

the

asked to maintain their usual diet and level of physical activity during the training period. Procedures

Anthropometric parameters, aerobic performance, and hematological profile were assessed at baseline and after the 9 weeks of HIIT and MCT. Anthropometric Measures. Body mass and stature were measured in underwear and without shoes. Stature (cm) was measured using a standing stadiometer (Seca les Mureaux, France) and recorded with a precision of 0.1 cm. Body mass (kg) was measured using a TPRO 3100 electronic balance (Terraillon) with a precision of 0.1 kg. Body mass index (BMI) was calculated for each participant using the following formula: body mass per stature2 (kg$m22). Skinfold thickness was measured using the mean (mm) of the 4 skinfold measurements (biceps, triceps, subscapular, and supra iliac) using a calibrated Harpenden caliper (Baty International, West Sussex, United Kingdom). Body density was estimated according to the equation of Durnin and Womersley (7). Subsequently, percentage body fat (%) was calculated from body density using the Siri (48) equation. Finally, lean mass (kg) was calculated by subtracting fat mass from body mass. Aerobic Capacity. Incremental Running Test. The VAMEVAL test (5) was adopted to determine the maximal aerobic velocity (MAV) and to estimate the maximal oxygen consumption (V_ O2max). It was performed on a 400-m running track marked every 20 m. Each participant began with a running speed of 8.5 km$h21, with consecutive speed increases of 0.5 km$h21 every minute until exhaustion (5). Each participant had to adjust his running velocity, in manner to find himself exactly at the beep at the correspondent cone. The test was terminated when the participant could no longer maintain the required speed imposed by the beep or when he accumulated 2 successive delays of 2 m of the cones/beeps. The maximal speed reached is significantly correlated with V_ O2max and maximal heart rate (HRmax). During the VAMEVAL test, heart rate was recorded using a heart rate monitor (Polar S810TM, Kempele, Finland). Training Programs. The training programs lasted 9 weeks in total and incorporated 3 training sessions per week (Wednesday, Friday, and Sunday) (27 sessions in total). Each training session was preceded by a standard warm-up including 15 minutes of jogging (50% of MAV) and 3 repetitions of 30 seconds of acceleration followed by 30 seconds of lightweight running and 5 minutes of dynamic stretching. High-Intensity Interval Training. Consisted of 30 seconds of running at 100% of MAV and 30 seconds of active recovery at 50% of MAV, in line with recommendations by Ouerghi et al. (37,38) First, the increase of the load was ensured by the increase of the training volume (number of repetitions) and then by increasing the training intensity (detailed in Table 2).

TM

Journal of Strength and Conditioning Research


MCT Before 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

17.6 6.0 5.4 11.4 0.7 2.72 8 0.4 1.14 3.14 2.51 0.84 0.91 1,614.17 1,170.75 452.03 124.8 55.3

After 68.1 22.3 13.0 58.6 15.5 56.03 189 5.1 14.51 44.65 88.26 32.49 28.67 5,912.5 3,039.25 2,249.13 455.5 168.63

6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

17.4 5.9 4.6 11.7 1.2 4.29 8 0.3 0.91 1.95 2.16 0.99 1.17 1,383 1,059.85 592.97 122.61 55.16

Before 67.5 22.4 14.5 57.6 14.4 52.31 189 5.2 15.45 46.59 89.95 33.13 29.80 6,962.5 3,730.25 2,628.88 424.63 178.75

6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

6.1 1.9 3.0 3.9 0.5 1.98 9 0.4 1.32 2.95 1.86 1.05 1.10 1,936.08 1,744.5 568.46 195.63 61.9

After

ANOVA

6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

0.87 0.97 0.53 0.78 0.39 0.39 0.89 0.99 0.29 0.53 0.14 0.12 0.05 0.49 0.45 0.51 0.22 0.56

66.8 22.2 14.1 57.3 14.9 54.08 188 5.1 15.23 45.79 89.76 33.24 29.83 5,350 2,916.13 2,052.88 268.88 112.13

6.2 1.9 2.1 4.6 0.7 2.72 9 0.4 1.13 2.67 2.42 0.99 1.25 921.18 992.4 386.519 99.16 74.12

_ O2max = maximal oxygen uptake; HRmax = *ANOVA = analysis of variance; BMI = body mass index; BF (%) = body fat; FFM = fat-free mass; MAV = maximal aerobic velocity, V maximal heart rate; RBC =red blood cells; Hb = hemoglobin; Hct = hematocrit; MCHC = mean corpuscular hemoglobin concentration; MCH = mean corpuscular hemoglobin; MCV = mean corpuscular volume; LE = leukocyte; NE = neutrophil; LY = lymphocyte; MO = monocyte; EO = eosinophil. †Data are expressed as mean 6 SD.

the

68.4 22.5 13.0 58.8 14.5 52.73 190 5.2 14.96 46.09 88.15 32.46 28.61 5,437.5 2,744 2,149.75 395.5 148.25

HIIT


Body mass (kg) BMI (kg$m22) BF (%) FFM (kg) MAV (km$h21) V_ O2max (ml$kg21$min21) HRmax (b$min21) RBC (millions$mm23) Hb (g$Dl21) Hct (%) MCV (fl) MCHC (g$dl21) MCH (pg) LE (mm3) NE (mm3) LY (mm3) MO (mm3) EO (mm3)

TM

3

| www.nsca.com

VOLUME 00 | NUMBER 00 | MONTH 2018 |


TABLE 1. Physical, physiological, and hematological biomarkers before and after 9 weeks in moderate-intensity continuous training (MCT) and high-intensity interval training (HIIT).*†

4

the

Moderate-Intensity Continuous Training. The continuous training program was design to ensure that HIIT and MCT sessions were matched for workload based on the total distance covered during the HIIT sessions as well as their averaged intensities (detailed in Table 2). Training load (TL) was calculated according to the formula by Impellizzeri et al. (18): TL = volume 3 intensity. However, for intermittent training session, the volume of training has been calculated by multiplying the duration of the effort by the number of repetitions, and the average intensity (AI) was calculated according to the formula by Saltin et al. (44), which has been successfully used by several other authors such as Oliveira et al. (36): AI = (RI + SI)/2 with AI: average intensity (%), RI: recovery intensity (%), and SI: stimulus intensity (%).

recovery at 50% of the MAV with each repetition. Each training session is composed of 3 sets at 6 reps each. (1:1): represents the ratio of the exercise period and the recovery period, which indicates that the period of work is equal to the period of active recovery.

MCT

*HIIT = high-intensity interval training; MAV = maximal aerobic velocity; R = recovery between sets; MCT = moderate-intensity continuous training. †Example: 3 3 (6 3 30 s) (1:1) (100: 50% MAV) means that each subject of intermittent group must run for 30 seconds at 100% of MAV followed by 30 seconds of active

3 3 (8 3 30 s) (1:1) (110:50% MAV) R = 5 min 24 min (80% MAV) 3 3 (8 3 30 s) (1:1) (100:50% MAV) R = 5 min 24 min (75% MAV) 3 3 (6 3 30 s) (1:1) (100:50% MAV) R = 5 min 18 min (75% MAV) HIIT

Weeks (4 + 5 + 6) Weeks (1 + 2 + 3)

TABLE 2. Specific load for intermittent and continuous training program.*†

Weeks (7 + 8 + 9)

Hematological Responses to Physical Training

Blood Sampling and Laboratory Analysis. While in a seated position, fasted venous blood samples were collected in precooled 4.9-ml EDTA monovets. Blood samples were collected at baseline and 2 days after the successful completion of the 9-week training programs. Importantly, blood samples were drawn in the fasting state on both occasions (baseline and end of the program), and a medical interrogatory was realized by a physician to ensure that the participants did not present any sickness that could have impacted the immune profile evaluation. Samples were immediately transported to the laboratory (Kef, Tunisia) for analysis (within 2 hours). Analysis was performed on an automated cell counter (Sysmex XN450; Norderstedt, Germany). Measured and calculated hematological parameters included red blood cell (RBC) count, hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration (MCHC), leukocyte (LE) count , neutrophil (NE) count , lymphocyte (LY) count , monocyte (MO) count , and eosinophil count. Statistical Analyses

The statistical analysis was performed using Stat View software (version 5 for windows), and the significance threshold was set at p , 0.05. All data are expressed as mean 6 SD. Data were checked for normality using the Kolmogorov-Smirnov test. A 2-way analysis of variance (ANOVA) with repeated measure has been performed to compare the data from the 2 groups before and after the intervention. Test de Mann-Whitney has been used to compare deltas (T1-T0) between HIIT and MCT groups.

RESULTS Sixteen healthy young men participated in this study. Their mean (6SD) values for age, stature, and body mass were 18.9 6 1.0 years, 1.74 6 0.06 m, and 68.02 6 12.8 kg, respectively. TM



the

TM


| www.nsca.com

Figure 1. Delta variation differences between T0 and T1 for the MCT and HIIT for LE, NE, LY, and MO. *p , 0.05; **p , 0.01; MCT = moderate-intensity continuous training; HIIT = high-intensity interval training; LE = leukocyte count; NE = neutrophil count; LY = lymphocyte count; MO = monocyte count.

No significant difference was found between the HIIT and MCT groups at baseline for body mass (67.5 6 6.1 vs. 68.4 6 17.6 kg, respectively), BMI (22.4 6 1.9 vs. 22.5 6 6 kg$m22, respectively), fat-free mass (FFM) (57.6 6 3.9 vs. 58.8 6 11.4 kg, respectively), and fat mass percentage (%FM) (14.5 6 3 vs. 13 6 5.4%, respectively). Physical fitness and hematological biomarkers were also similar between groups at baseline. Both the HIIT or MCT programs did not alter total body mass, BMI, FFM, and %FM as detailed in Table 1. Furthermore, there was no significant difference in D body mass, D BMI, D FFM, and D %FM between the HIIT (20.69 6 0.99 kg, 20.23 6 0.33 kg$m22, 20.25 6 1.11 kg, and 20.43 6 1.29%, respectively) and MCT interventions (20.35 6 0.65 kg, 20.11 6 0.22 kg$m22, 20.23 6 0.90 kg and 0.01 6 1.23%, respectively). Similarly MAV and V_ O2max did not change between T0 and T1 in HIIT and MCT groups (Table 1), with no significant difference between groups for their delta (D MAV: 0.50 6 0.53 vs. 0.94 6 1.02 km$h21

and D V_ O2max: 1.76 6 1.86 vs. 3.31 6 3.57 ml$kg21$min21, for HIIT and MCT groups, respectively). Although no significant change was observed in the components of white blood cells or red blood cells in both the HIIT and MCT groups between T0 and T1 (Table 1); the results, however, revealed significant differences in D LE (p , 0.01), D NE (p , 0.05), D LY (p , 0.05), and D MO (p , 0.01) between the HIIT (21,613 6 1,886 mm3, 2814 6 1770 mm3, 2576 6 777 mm3, and 2156 6 172 mm3, respectively) and MCT (475 6 471 mm3, 295 6 348 mm3, 99 6 288 mm3, and 60 6 78 mm3, respectively) interventions. The Figure 1 illustrates the differences between the MCT and HIIT groups regarding the variations (deltas) of these hematological parameters (Figure 1). Our results also revealed a positive relationship between initial weight, FFM, and D LE and between initial %FM and D MO in our HIIT group. We can note a negative relationship between D MAV and D V_ o2max and weight VOLUME 00 | NUMBER 00 | MONTH 2018 |


5

Hematological Responses to Physical Training (r = 20.85, r = 20.82; respectively), BMI (r = 20.76, r = 20.82; respectively), and FFM (r = 20.88, r = 20.88; respectively) at T0 (p , 0.05), and a positive relationship between D RBC and D Hb and body mass (r = 0.83, r = 0.84; respectively), BMI (r = 0.82, r = 0.91; respectively), and FFM (r = 0.84, r = 0.85; respectively) at T0 (p , 0.05). Similarly, we can note a positive relationship between D Hct, D MCHC, and initial body mass (r = 0.74 and r = 0.89, respectively; p , 0.05). Initial BMI was correlated with D LY (r = 0.73, p , 0.05), and initial FFM was positively correlated with D Hct (r = 0.76, p , 0.05).

DISCUSSION The main objective of this pilot study was to compare measures of aerobic capacity and hematological profile at baseline and after 9 weeks of MCT and HIIT training in healthy active young men. According to our results, 9 weeks of MCT and HIIT have significantly different effects on the immune profile of healthy active young men. The main immune biomarkers, LE, LY, NE, and MO counts were increased after the 9-week MCT intervention compared with the matched total workload HIIT intervention. Indeed, although our initial groupbased analysis (ANOVA) missed to show any difference between groups, the variations of these parameters seemed significantly better in the MCT group (using a delta approach). Evidences remained somehow contractive regarding the effects of physical training on the body composition of normal weight subjects. In an early study from, Gregory (13), continuous training and interval training performed at the same total workload were both presented as ineffective to induce body mass change in healthy young men. Similarly, later results from Gorostiaga et al. (12) observed that 8 weeks of interval or continuous training at the same relative work intensities had no effect on body mass in young adults. Mazurek et al. (27), however, demonstrated that moderate continuous cycle exercise is more effective than HIIT for the management of body composition in young women. According to our results, a 9-week HIIT or MCT did not improve body composition in healthy active young men. A plausible explanation could be the adoption of compensatory behaviors by individuals in response to chronic physical exercise, such as increased energy consumption or reduced spontaneous physical activity and thus energy expenditure, which then have implications for weight loss or body composition modifications (29,42). Indeed, there is evidence that chronic physical activity interventions might favor compensatory responses, whereby individuals tend to reduce their daily activity (outside the prescribed sessions) leading to unchanged daily energy expenditure despite the imposed physical activity intervention (22,28,31,52). Furthermore, some researches have shown increased fasting and postprandial hunger profiles as well as increased food reward behaviors in response to regular physical activity and indeed more

6

the

so in relation to high-intensity exercise programs, suggesting increased daily energy intake (26,29,46). Importantly, Miguet et al. recently demonstrated that 12 weeks of both HIIT and moderate-intensity exercise favored significant increases in daily food consumption in overweight and obese adolescents (30). Future studies should seek to explore the energetic compensatory responses to chronic exercise of differing intensities to help explain modifications (if any) in body composition. Although weight loss is not the main objective in normal weight individuals, physical activity remains necessary to maintain or improve their physical fitness and metabolic profile, preventing then cardiovascular and metabolic diseases. Interestingly, although there is a growing interest for HIIT interventions among various healthy and pathological populations, most of the studies conducted so far have explored its impacts on fitness and metabolic health (3,8,37,38), but few ones have been interested in the effect of HIIT program on the hematological profile. Our study shows a significant decrease in the number of LE, LY, NE, and MO after the HIIT program and a significant increase of these cell numbers after the MCT program. In addition, the comparison of deltas showed significant difference in D LE, D LY, D NE, and D MO between the 2 groups. Although this study was to the best of our knowledge the first to compare HIIT and MCT programs of similar workload, our results agree with previous studies suggesting that moderate training sessions improved the immunity components (25,47). However, other studies noted that vigorous chronic exercises were associated with a significant depression of the systemic and mucosal immunity (10,24,25), which might increase the participants’ susceptibility for health issues, which in turn might affect their performances, especially during infection transmission seasons. Nieman et al. (35) showed that 15 weeks of moderate training (brisk walking at 60% heart rate reserve) improved NK cell activity and reduced upper respiratory tract infection symptomatology in sedentary women. By contrast, Gleeson et al. (11) demonstrated that 7 months of intensive training induced a chronic suppression of both systemic (significant fall in NK cell numbers and percentages) and mucosal (suppression of serum IgA, IgG and IgM, and salivary IgA concentration) immunity in elite swimmers. This immune fragility induced an increase in respiratory infections in the intensive training period. According to Gleeson, the mechanisms responsible for this phenomenon of immune suppression are still unknown and might be explained by hormonal changes associated with exhausting exercise. According to the “J-shape” curve theoretical model proposed by Nieman describing the relationship between the intensity of training and the risk of infection of the upper respiratory tract, the incidence of respiratory infections was higher among people who practice strenuous physical activity compared with those engaged in moderate training sessions (32). According to Fisher-Wellman and Bloomer (9),

TM



the

TM

Journal of Strength and Conditioning Research this may be due to an overproduction of reactive oxygen/ nitrogen species through several pathways including muscular damages, mitochondrial respiration, prostanoid metabolism, the auto-oxidation of catecholamine, and the oxidase enzymatic activity (19). Although aerobic capacities have been assessed in these studies, our results do not show any significant improvement in response to both interventions, which was contradictory with the literature. Indeed, evidences comparing intermittent and continuous training programs matched (13,17,51) or not for the workload (1,40,50) point increase aerobic fitness. This absence of modification of the participants’ MAV and V_ O2max after both our MCT and HIIT interventions might be directly explained by the use of an indirect filed test (“VAMEVAL”) with limited sensitivity to changes, whereas direct laboratory-based methods would have been more adapted and precise. Other limitations must be considered when interpreting our results. Although this was a pilot study, the relatively small sample might have underpowered the detection of significant changes for some variables. In addition, as suggested below, it would have been important to assess our participants’ daily intake at regular intervals during the intervention and by the end of the program to evaluate any potential compensatory responses.

PRACTICAL APPLICATIONS High-intensity interval training is nowadays advocated as an efficient training modality, especially because of its timeefficient nature. Although its effects on body composition and physical fitness are well documented, its impact on immune responses is less explored. Accordingly, our results clearly indicate that the impact exercise has on the immune system must be considered by practitioners and coaches. Individuals involved in regular exercise should be educated regarding the effect intensive training programs can have on the immune system to prevent them from experiencing any unnecessary health complications. Nieman (34). proposed a set of recommendations to be respected (e.g., keep other life stresses to a minimum; avoid overtraining and chronic fatigue; and influenza vaccination during the winter months, etc.) that should be followed by both participants and practitioners. To conclude, this pilot study was the first to compare the effect of HIIT and MCT matched for physical workload on the hematological profile of healthy active young men. Our results suggest that 9 weeks of MCT, unlike a 9-week period of HIIT, does not compromise immune response in healthy active young men. These findings may have important implications for individuals who are recreationally active regarding susceptibility to infection depending on training intensity choice. Further research, however, is required to establish the mechanisms responsible for the suppressed immune response to prolonged (.9 weeks) intensive exercise (33).

| www.nsca.com

ACKNOWLEDGMENTS The authors acknowledge all the participants who volunteered to take part in this study. The authors have no financial relationships relevant to this article to disclose.

REFERENCES 1. Baquet, G, Gamelin, FX, Mucci, P, The´venet, D, Van Praagh, E, and Berthoin, S. Continuous vs. interval aerobic training in 8- to 11-yearold children. J Strength Cond Res 24: 1381–1388, 2010. 2. Bassett, DR Jr and Howley, ET. Limiting factors for maximum oxygen uptake and determinants of endurance performance. Med Sci Sports Exerc 32: 70–84, 2000. 3. Ben Abderrahman, A, Prioux, J, Chamari, K, Ben Ounis, O, Tabka, Z, and Zouhal, H. Running interval training and estimated plasmavolume variation. Int J Sports Physiol Perform 8: 358–365, 2013. 4. Berthoin, S, Mante´ca, F, Gerbeaux, M, and Lensel-Corbeil, G. Effect of a 12-week training programme on Maximal Aerobic Speed (MAS) and running time to exhaustion at 100% of MAS for students aged 14 to 17 years. J Sports Med Phys Fitness 35: 251–256, 1995. 5. Cazorla, G. Field tests to evaluate aerobic capacity and maximal aerobic speed. In: Proceedings of the International Symposium of Guadeloupe. Edts: Actshng and Areaps Pointe-a`-Pitre, France, 1990. pp. 151–173. 6. Daussin, FN, Ponsot, E, Dufour, SP, Lonsdorfer-Wolf, E, Doutreleau, S, Geny, B, et al. Improvement of VO2max by cardiac output and oxygen extraction adaptation during intermittent versus continuous endurance training. Eur J Appl Physiol 101: 377–383, 2007. 7. Durnin, JV and Womersley, J. Body fat assessed from total body density and its estimation from skinfold thickness: Measurements on 481 men and women aged from 16 to 72 years. Br J Nutr 32: 77–97, 1974. 8. Fisher, G, Brown, AW, Bohan Brown, MM, Alcorn, A, Noles, C, Winwood, L, et al. High intensity interval- vs moderate intensitytraining for improving cardiometabolic health in overweight or obese males: A Randomized Controlled Trial. PLoS One 10: e0138853, 2015. 9. Fisher-Wellman, K and Bloomer, RJ. Acute exercise and oxidative stress: A 30 year history. Dyn Med 8: 1–25, 2009. 10. Gleeson, M. Immune function in sport and exercise. J Appl Physiol 103: 693–699, 2007. 11. Gleeson, M, McDonald, WA, Cripps, AW, Pyne, DB, Clancy, RL, and Fricker, PA. The effect on immunity of long-term intensive training in elite swimmers. Clin Exp Immunol 102: 210–216, 1995. 12. Gorostiaga, EM, Walter, CB, Foster, C, and Hickson, RC. Uniqueness of interval and continuous training at the same maintained exercise intensity. Eur J Appl Physiol Occup Physiol 63: 101–117, 1991. 13. Gregory, LW. The development of aerobic capacity: A comparison of continuous and interval training. Res Q 50: 199–206, 1979. 14. Hasani, A and Soleimanian, K. The effect of progressive endurance training and Silymarin consumption on hematological parameters. Sci J Iran Blood Transfus Organ 11: 155–163, 2014. 15. Helgerud, J, Høydal, K, Wang, E, Karlsen, T, Berg, P, Bjerkaas, M, et al. Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc 39: 665–671, 2007. 16. Heyward, VH and Gibson, AL. Advanced Fitness Assessment and Exercise Prescription (7th ed.): Human Kinetics, Champain, IL, USA 2014. pp. 135. 17. Iellamo, F, Manzi, V, Caminiti, G, Vitale, C, Castagna, C, Massaro, M, et al. Matched dose interval and continuous exercise training induce similar cardiorespiratory and metabolic adaptations in patients with heart failure. Int J Cardiol 167: 2561–2565, 2013. 18. Impellizzeri, FM, Rampinini, E, Coutts, AJ, Sassi, A, and Marcora, SM. Use of RPE-based training load in soccer. Med Sci Sports Exerc 36: 1042–1047, 2004. VOLUME 00 | NUMBER 00 | MONTH 2018 |


7

Hematological Responses to Physical Training 19. Jackson, MJ. Exercise and oxygen radical production by muscle. In: Handbook of Oxidants and Antioxidants in Exercise. CK Sen, L Packer and O Ha¨nninen, eds. Amsterdam, the Netherlands: Elsevier Science, 2000. pp: 57–68. 20. Jones, AM and Carter, H. The effect of endurance training on parameters of aerobic fitness. Sports Med 29: 373–386, 2000. 21. Kehat, I, Shupak, A, Goldenberg, I, and Shoshani, O. Long-term hematological effects in Special Forces trainees. Mil Med 168: 116– 119, 2003. 22. King, NA, Caudwell, P, Hopkins, M, Byrne, NM, Colley, R, Hills, AP, et al. Metabolic and behavioral compensatory responses to exercise interventions: Barriers to weight loss. Obesity (Silver Spring) 15: 1373–1383, 2007. 23. Koubaa, A, Trabelsi, H, Masmoudi, L, Elloumi, M, Sahnoun, Z, Zeghal, KM, et al. Effect of intermittent and continuous training on body composition cardiorespiratory fitness and lipid profile in obese adolescents. Iosr J Pharm 3: 31–37, 2013. 24. Li, TL, Lin, HC, Ko, MH, Chang, CK, and Fang, SH. Effects of prolonged intensive training on the resting levels of salivary immunoglobulin A and cortisol in adolescent volleyball players. J Sports Med Phys Fitness 52: 569–573, 2012.

omentin-1 concentration in overweight/obese and normal-weight youth. Obes Facts 10: 323–331, 2017. 38. Ouerghi, N, Fradj, MKB, Khammassi, M, Feki, M, Kaabachi, N, and Bouassida, A. Plasma chemerin in young untrained men: Association with cardio-metabolic traits and physical performance, and response to intensive interval training. Neuro Endocrinol Lett 38: 59–66, 2017. 39. Ouerghi, N, Khammassi, M, Boukorraa, S, Feki, M, Kaabachi, N, and Bouassida, A. Effects of a high-intensity intermittent training program on aerobic capacity and lipid profile in trained subjects. Open Access J Sports Med 10: 243–248, 2014. 40. Robinson, E, Durrer, C, Simtchouk, S, Jung, ME, Bourne, JE, Voth, E, et al. Short-term high-intensity interval and moderate-intensity continuous training reduce leukocyte TLR4 in inactive adults at elevated risk of type 2 diabetes. J Appl Physiol (1985) 119: 508–516, 2015. 41. Romeo, J, Wa¨rnberg, J, Pozo, T, and Marcos, A. Physical activity, immunity and infection. Proc Nutr Soc 69: 390–399, 2010. 42. Rowland, TW. The biological basis of physical activity. Med Sci Sports Exerc 30: 392–399, 1998.

25. Mackinnon, LT. Chronic exercise training effects on immune function. Med Sci Sports Exerc 32: S369–S376, 2000.

43. Said, M, Feki, Y, Aouni, Z, Machghoul, S, Hamza, M, and Amri, M. Effects of sustained intensive physical activities on immune cells circulating and pro-inflammatory cytokines production in trained and untrained humans. Sci Sports 24: 229–237, 2009.

26. Martins, C, Aschehoug, I, Ludviksen, M, Holst, J, Finlayson, G, Wisloff, U, et al. High-intensity interval training, appetite, and reward value of food in the obese. Med Sci Sports Exerc 49: 1851– 1858, 2017.

44. Saltin, B, Essen, B, and Pedersen, P. Intermittent exercise: Its physiology and some practical applications. In: Advances in Exercise Physiology. E Joekle, R Anandand, and H Stoboy, eds. Basel, Switzerland: Karger Publishers, 1976. pp. 23–51.

27. Mazurek, K, Zmijewski, P, Krawczyk, K, Czajkowska, A, Ke˛ska, A, ´ Kapu´scinski, P, et al. High intensity interval and moderate continuous cycle training in a physical education programme improves health-related fitness in young females. Biol Sport 33: 139– 144, 2016.

45. Santhiago, V, da Silva, AS, Papoti, M, and Gobatto, CA. Responses of hematological parameters and aerobic performance of elite men and women swimmers during a 14-week training program. J Strength Cond Res 23: 1097–1105, 2009.

28. Meijer, EP, Westerterp, KR, and Verstappen, FT. Effect of exercise training on total daily physical activity in elderly humans. Eur J Appl Physiol Occup Physiol 80: 16–21, 1999. 29. Melanson, EL, Keadle, SK, Donnelly, JE, Braun, B, and King, NA. Resistance to exercise-induced weight loss: Compensatory behavioral adaptations. Med Sci Sports Exerc 45: 1600–1609, 2013.

46. Alkahtani, SA, Byrne, NM, Hills, AP, and King, NA. Interval training intensity affects energy intake compensation in obese men. Int J Sport Nutr Exerc Metab 24: 595–604, 2014. 47. Shimizu, K, Kimura, F, Akimoto, T, Akama, T, Tanabe, K, Nishijima, T, et al. Effect of moderate exercise training on T-helper cell subpopulations in elderly people. Exerc Immunol Rev 14: 24–37, 2008. 48. Siri, WE. The gross composition of the body. Adv Biol Med Phys 4: 239–280, 1956.

30. Miguet, M, Masurier, J, Julian, V, Metz, L, Chaplais, E, Cardenoux, C, et al. Moderate versus High Intensity Interval Exercise trainings on Energy intake and appetite feelings in adolescents with obesity. Obes Facts 10: 1–274, 2017.

49. Szygula, Z. Erythrocytic system under the influence of physical exercise and training. Sports Med 10: 181–197, 1990.

31. Morio, B, Montaurier, C, Pickering, G, Ritz, P, Fellmann, N, Coudert, J, et al. Effects of 14 weeks of progressive endurance training on energy expenditure in elderly people. Br J Nutr 80: 511–519, 1998.

50. Tanisho, K and Hirakawa, K. Training effects on endurance capacity in maximal intermittent exercise: Comparison between continuous and interval training. J Strength Cond Res 23: 2405–2410, 2009.

32. Nieman, DC. Exercise, upper respiratory tract infection, and the immune system. Med Sci Sports Exerc 26: 128–139, 1994.

51. Tuimil, JL, Boullosa, DA, Ferna´ndez-del-Olmo, MA, and Rodrı´guez, FA. Effect of equated continuous and interval running programs on endurance performance and jump capacity. J Strength Cond Res 25: 2205–2211, 2011.

33. Nieman, DC. Immune response to heavy exertion. J Appl Physiol 82: 1385–1394, 1997. 34. Nieman, DC. Is infection risk linked to exercise workload? Med Sci Sports Exerc 32: S406–S411, 2000. 35. Nieman, DC, Nehlsen-Cannarella, SL, Markoff, PA, BalkLamberton, AJ, Yang, H, Chritton, DB, et al. The effects of moderate exercise training on natural killer cells and acute upper respiratory tract infections. Int J Sports Med 11: 467–473, 1990. 36. Oliveira, BR, Slama, FA, Deslandes, AC. Furtado, ES, and Santos, TM. Continuous and high-intensity interval training: Which promotes higher pleasure? PLoS One 8: e79965, 2013. 37. Ouerghi, N, Ben Fradj, MK, Bezrati, I, Feki, M, Kaabachi, N, and Bouassida, A. Effect of high-intensity interval training on plasma

8

the

52. Wang, X and Nicklas, BJ. Acute impact of moderate-intensity and vigorous-intensity exercise bouts on daily physical activity energy expenditure in postmenopausal women. J Obes 2011: 342431, 2011. 53. Warburton, DE, Haykowsky, MJ, Quinney, HA, Blackmore, D, Teo, KK, Taylor, DA, et al. Blood volume expansion and cardiorespiratory function: Effects of training modality. Med Sci Sports Exerc 36: 991–1000, 2004. 54. Yasaswini, B, Viswanath Reddy, A, and Madhavi, K. Effect of continuous endurance training versus intermittent endurance training on aerobic capacity in recreational female hockey players a randomized control trail. Int J Sci Res 5: 1639–1642, 2016.

TM

