impact-of-short-and-moderate-rest-intervals-part-ii

J Strength Cond Res 306: 1570–1576, 2016—The purpose of this study was to inves-tigate the influence of short and moderate recovery intervals during heavy strength exercise on performanc

ON THE A CUTE I MMUNOMETABOLIC R ESPONSE TO

JOSEGEROSA-NETO,1 FABRI´CIO E ROSSI,1 EDUARDO Z CAMPOS,1 BARBARA M.M ANTUNES,1

JASONM CHOLEWA,2 ANDFABIO S LIRA1

1Exercise and Immunometabolism Research Group, Department of Physical Education, Univer Estadual Paulista (UNESP),

Presidente Prudente, SP, Brazil; and2Department of Kinesiology, Recreation, and Sport Studies, Coastal Carolina University,

Conway, South Carolina

ABSTRACT

Gerosa-Neto, J, Rossi, FE, Campos, EZ, Antunes, BMM,

Cholewa, JM, and Lira, FS Impact of short and moderate rest

intervals on the acute immunometabolic response to

exhaus-tive strength exercise: Part II J Strength Cond Res 30(6):

1570–1576, 2016—The purpose of this study was to

inves-tigate the influence of short and moderate recovery intervals

during heavy strength exercise on performance, inflammatory,

and metabolic responses in recreational weightlifters Eight

healthy subjects (age = 24.66 4.1 years) performed 2

ran-domized sequences with different rest intervals: short = 90%

of 1RM and 30 seconds rest allowed between sets; moderate

= 90% of 1RM and 90 seconds rest allowed between sets

All sequences of exercises were performed over 4 sets until

movement failure in the squat and bench press exercises,

respectively Glucose, TNF-a, IL-6, IL-10, IL-10/TNF-a ratio,

and nonester fatty acid concentrations were assessed at the

baseline, immediately postexercise, post-15 and post-30

mi-nutes We observed a statistically significant decrease after

30 seconds on maximum number of repetitions (p = 0.003)

and total weight lifted (p = 0.006) after the bench press, and

there was a marginal decrease in the squat (p = 0.055) The

glucose concentrations showed a significant increase

post-15 minutes in the 30-second condition (pre-exercise = 86.1

6 9.1, immediately = 85.3 6 8.2, 15 = 97.0 6 9.0,

post-30 = 87.16 5.3 mg/dl; p = 0.015); on the other hand, IL-10

increased post-30 minutes in the 90-second condition

(pre-exercise = 18.26 12.7, immediately = 16.4 6 10.7, post-15

= 16.86 12.2, post-30 = 35.0 6 13.1 pg/ml; p , 0.001) In

addition, the 90-second condition showed anti-inflammatory

effects (as indicated by IL-10/TNF-a ratio: pre-exercise =

1.08 6 1.32, immediately = 1.23 6 1.20, post-15 = 1.15

6 1.14, post-30 = 2.48 6 2.07; p = 0.020) compared with the 30-second condition (pre-exercise = 1.306 2.04, imme-diately = 0.996 1.27, post-15 = 1.23 6 1.82, post-30 = 1.286 1.28; p = 0.635) Thus, we concluded that a moderate interval of recovery (90 seconds) during heavy strength exer-cise allowed higher workload, IL-10 levels, and IL-10/TNF-a ratio in recreational weightlifters

KEY WORDSinterval of recovery, inflammation, metabolism

INTRODUCTION

The stimuli generated in strength training

proto-cols cause changes in the production and release

of hormones and cytokines because of an increase in energetic demand and skeletal mus-cle injury (3) The acute immunological response to train-ing plays a role in energy metabolism (10), skeletal muscle repair and remodeling, and the anabolic/catabolic response, and may respond differently according the type

of exercise, intensity, volume and recovery between exer-cise bouts (9,13)

Philips et al (12) compared strength training sets on the same 8 exercises with different intensities (2 sets of 12 repetitions followed by a third set to fatigue at 65% 1 repetition maximum [1RM], and 2 sets of 8 repetitions and with a third set to fatigue at 85% 1RM) and observed increases in IL-6 concentrations after both intensities

When the load volume is matched, IL-6 elevation is sim-ilar between different intensities (15) Recently, our group demonstrated the influence of interval length on immuno-metabolic responses in recreational weightlifters (13)

Pooled IL-6 concentrations (i.e., cluster of all periods in each variable) were higher after 4 sets at 70% of 1RM performed until exhaustion with 90-second recovery com-pared with 30-second recovery However, no increase was observed in TNF-a, IL-6, or IL-10 Thus, because muscle IL-6 release might be related with anti-inflammatory

Address correspondence to Fabrı´cio E Rossi, rossifabricio@yahoo.

com.br.

30(6)/1570–1576

Journal of Strength and Conditioning Research

Ó 2016 National Strength and Conditioning Association

status and muscle protein synthesis (12), moderate

inter-vals may be better to induce positive adaptations (13)

The immunometabolic response to more intense strength

training sets (i.e., 90% of 1RM) requires further investigation;

however, especially because total volume (an important

variable to immunometabolic alteration) decreases with

higher intensities (15) and a higher metabolic demand may

modify the anti-inflammatory status (3) Moreover,

under-standing the immunometabolic response in terms of

sub-strate availability and adaptation during sets of heavy

strength exercise is important to adjust/modify the strength

training periodization to ensure the correct adaptation is

being pursued because 90% of 1RM and 30–90 seconds of

recovery interval is extensively used during strength training

Thus, the purpose of this study was to investigate the

influence of short (30-second) and moderate (90-second)

recovery intervals during sets of heavy strength exercise

performed until exhaustion on inflammatory and metabolic

responses in recreational weightlifters Our hypothesis is that

a high-intensity strength exercise session with moderate

recovery intervals (90-second) can induce a positive

inflam-matory response compared with short recovery intervals

(30-second) because of higher IL-10 levels that result from

the higher metabolic demands

METHODS

Experimental Approach to the Problem

To investigate the effect of 2 different rest periods between

sets (30 and 90 seconds) on the immunometabolic response,

data were collected using a randomized and

counterbal-anced within-subjects design Subjects performed the 2

exercise sessions at 72 hours intervals The test of 1RM

was determined on nonconsecutive days, 1 week before the

exercise protocols for all subjects The blood samples were

collected pre-exercise, immediately after exercise, and

post-15 minutes and post-30 minutes into recovery (Figure 1)

Subjects

Eight male subjects with strength training experience (.6

months) (1) voluntarily participated in this study All subjects

performed weight training with a mean frequency of 4

sessions per week for approximately 1 hour per session Inclusion criteria for participation in the study were the following: age between 20 and 32 years, and no contra-indications involving the cardiovascular system, muscles, joints, or bones of the lower limbs with regard to the prac-tice of strength training This study was conducted in accordance with the Helsinki Declaration Approval for the study was obtained from the appropriate Institutional Review Board (IRB) Informed consent was obtained from all participants before their participation The study con-forms to the Code of Ethics of the World Medical Associ-ation (approved by the ethics advisory board of Swansea University) and required players to provide informed con-sent before participation

Procedures

Anthropometric Measurements and Dietary Intake Assessment Anthropometry consisted of body weight and height measurements Height was measured on a fixed stadiometer

of the Sanny brand with an accuracy of 0.1 cm and a length

of 2.20 m Body weight was measured using an electronic scale (Filizola PL 50; Filizola Ltda., Brazil), with a precision

of 0.1 kg

Diet was not standardized; however, participants were required to eat 3 hours before all testing sessions Partic-ipants were instructed by a nutritionist how to complete the food records and were required to record all foods con-sumed on the day of each testing session Nutrition data were analyzed for energy intake and macronutrient distri-bution using the NutWin software, version 1.5 (Programa de Apoio a` Nutric¸a˜o, Universidade Federal de Sa˜o Paulo, Brazil, 2002)

Test of One Repetition Maximum One week before testing, the participants performed 4 sets of 10–12 repetition in each exercise, 3 times per week (Monday, Wednesday and Friday) for familiarization with equipment The test of 1RM was performed using the squat and bench press exercises The 1RM test consisted of 5 minutes of warm-up (jogging), fol-lowed by the performance of 1 set of 10 repetitions of each exercise at approximately 50% of the 1RM The load was

increased gradually (10–15%) during the test until the partic-ipants were no longer able to perform the entire movement, and 3–5 attempts were allowed (1) For recovery, an interval of 3–5 minutes between attempts was given (1) No rest was al-lowed between the concentric and eccentric phases of the movement, and the partici-pants were encouraged ver-bally to exert a maximum effort In addition, for better

Figure 1 Study design.

control of the 1RM test procedures, a wooden seat with

adjustable heights was placed behind the participant to keep

the bar displacement and knee angle (;908) constant on

each half-squat repetition Two fitness professionals super-vised all testing sessions

Experimental Protocol At 72 hours after the 1RM test, subjects performed 2 randomized exercise sessions separated

by 72 hours interval Before the exercise sessions, 5 minutes

of warm-up (jogging) was performed During the exercise sessions, subjects were verbally encouraged to perform all sets until exhaustion in each exercise

The exercise order for all sessions was squats followed by bench press In both conditions, subjects performed 4 sets of squat and then 4 sets of bench press using 90% of the 1RM

In the short interval, 30 seconds (30-second) of rest was allowed between sets and exercises; whereas in the moderate interval, 90 seconds (90-second) of rest was allowed between

TABLE1.Subject characteristics

Variables Mean6 SD (n = 8)

Age (yr) 25.26 4.1

Height (cm) 178.16 10.4

Weight (kg) 76.46 7.7

Fat mass (%) 18.36 6.1

Fat free mass (%) 77.26 5.7

Figure 2 Comparison of the maximum number of repetitions at the squat (A), bench press (B), total weight lifted at the squat (C), bench press (D), and

maximum number of repetitions in each series at the squat (E) and bench press (F) a = Tukey’s post hoc test with p-value # 0.05 compared with series-1; b =

Tukey’s post hoc test with p-value # 0.05 compared with series-2 Student’s t-test for independent samples was performed and repeated measurements were

conducted for the analyses when necessary.

sets and exercises All the sequences of exercises were

performed for 4 sets until movement failure for each exercise

with normal speed (1-second eccentric and 1-second

con-centric actions with 1-second pause between each

repeti-tion) (16) The total number of repetitions performed was

recorded for each set of each exercise and for all sequences

and used to analyze workload and performance All the

se-quences of exercises were performed 3 hours after prandial

Blood Samples and Analysis Blood samples were collected at

rest, immediately, 15 and 30 minutes after acute exercise

sessions The blood samples (10 ml) were immediately

allocated into two 5 ml vacutainer tubes (Becton

Dick-inson, Juiz de Fora, Brazil) containing EDTA for plasma

separation and into one 5 ml dry vacutainer tube for serum

separation The tubes were centrifuged at 3,000 RPM for

15 minutes at 48 C, and plasma and serum samples were

stored at 2208 C until analysis Glucose was assessed

through a commercial enzymatic kit (Labtest, Sa˜o Paulo,

Brazil) Nonester fatty acid (NEFA) was assessed by a

col-orimetric method with a commercial kit (Wako

Diagnos-tics, CA, USA) Cytokines (IL-6, IL-10, and TNF-a) were

assessed using ELISA commercial kits

(Affymetrix/eBio-science, Ambriex S/A, Brazil) IL-6, IL-10, TNF-a, and

glucose were assessed using serum, and NEFA was

as-sessed using plasma To eliminate interassay variance, all

samples were analyzed in identical runs resulting in an

intra-assay variance of ,7% Standard curve range for

TNF-a (7.81–500 pg/ml), IL-6 (3.12–200 pg/ml) and

IL-10 (4.68–300 pg/ml), NEFA (0.01–4.00 mEq/L), and for glucose reference standard was 100 mg/dl

Statistical Analyses

The data normality was verified using the Shapiro–Wilk test The comparison of the total weight lifted the maxi-mum number of repetitions under the different conditions and food intake was analyzed using the Student’s t-test for independent samples The comparison of the maximum number of repetitions in each series was conducted by repeated measurements analyses and the differences in the glucose, NEFA and cytokines were calculated perform-ing a 2-way repeated measure of ANOVA (group3 time) When a significant difference in group or interaction was observed, a Tukey’s post hoc test was conducted For all measured variables, the estimated sphericity was verified according to Mauchly’s W test, and the Greenhouse– Geisser correction was used when necessary Statistical significance was set at p # 0.05 The data were analyzed using the Biostat (version 5.0)

RESULTS

The mean6 SD values of the subjects’ characteristics are presented in Table 1 Total food intake and macronutrient distribution 3 hours before the test (expressed in kcal) were similar between conditions (30-second = 870.5 6 525.6 Kcal vs 90-second = 836.2 6 593.8 Kcal; p = 0.906) (carbohydrates: 30-second = 123.7 6 118.3 vs 90-second = 124.3 6 6.4 grams, p = 0.992; protein:

Figure 3 Comparison of the IL-6 (A), IL-10 (B), TNF- a (C), and IL-10/TNF-a ratio (D) immediately after exercise (immediately), 15 minutes,

post-30 minutes into recovery Two-way analysis of variance (condition 3 time) with repeated measurements of the second factor.

30-second = 45.0 6 27.7 vs 90-second = 38.1 6 32.8

grams, p = 0.657; lipids: 30-second = 18.1 6 10.1 vs

90-second = 24.96 11.1 grams, p = 0.210)

Figure 2 presents the maximum number of repetition and

total weight lifted during squat (Figures 2A, C) and bench

press (Figures 2B, D) in both conditions Figures 2E, F

showed the volume decrement during the sets of squat

and bench press during 30-second and 90-second,

respec-tively There were significant differences between conditions

for maximal number of repetitions (30 seconds = 8.66 2.7 3

90 seconds = 14.46 3.8 repetitions) and total weight lifted

(30 seconds = 650.4 6 224.9 3 90 seconds = 1.080.5 6

305.3 kg) in the bench press; however, there was a marginal

decrease in squat for maximal number of repetitions (30

seconds = 196 9.7 3 90 seconds = 32 6 14.5 repetitions)

and total weight lifted (30 seconds = 3.253.56 1.577.8 3 90

seconds = 5.926.86 3.255.4 kg)

The cytokines are presented in Figure 3 IL-10 increased

at post-30 in the 90-second condition (pre-exercise = 18.26

12.7 pg$ml21, immediately = 16.4 6 10.7 pg$ml21,

post-15 = 16.86 12.2 pg$ml21, and post-30 = 35.0 6 13.1 pg$ml21; p , 0.001) but with-out significant differences in the 30-second condition (pre-exercise = 17.06 10.0 pg$ml21, immediately = 16.6 6 10.9 pg$ml21, post-15 = 15.3 6 10.0 pg$ml21, and post-30 = 23.1 6 15.1 pg$ml21; p = 0.091) In addition, the IL-10/

TNF-a ratio showed increases only at post-30 in the 90-second condition (pre-exercise

= 1.086 1.32, immediately = 1.236 1.20, post-15 = 1.15 6 1.14, post-30 = 2.486 2.07; p = 0.020), but not in the 30-second condition (pre-exercise

= 1.30 6 2.04, immediately = 0.996 1.27, post-15 = 1.23 6 1.82, post-30 = 1.286 1.28; p = 0.635)

Glucose increased in the 30-second condition at 15 mi-nutes after exercise (pre-exer-cise = 86.1 6 9.1 mg$dl21, immediately = 85.3 6 8.2 mg$dl21, post-15 = 97.0 6 9.0 mg$dl21, and post-30 = 87.1 6 5.3 mg$dl21; p = 0.015) but there were no sig-nificant differences in the 90-second condition (pre-exercise = 84.2 6 8.5 mg$dl21, immediately = 89.6 6 13.1 mg$dl21, post-15 = 90.66 11.4 mg$dl21, and post-30 = 86.36 13.2 mg$dl21;

p = 0.758) There were no significant differences between time and condition for TNF-a and NEFA, but there was

a tendency in IL-6 during 30-second condition There were no interactions (time 3 condition) for any of the variables analyzed (Figure 4)

DISCUSSION

The aim of the present study was to investigate the effects of short (30 seconds) and moderate (90 seconds) recovery intervals during sets of heavy strength exercise on inflam-matory and metabolic responses in recreational weightlifters

The main findings of the present study were that (a) both exercise sessions did not change IL-6, TNF-a, and NEFA;

(b) 30-second induced a greater increase in glucose concen-trations 15 minutes after exercise; and (c) 90-second pro-moted an increase in IL-10 concentrations and the IL-10/

TNF-a ratio in relation to baseline during heavy strength exercise in recreational weightlifters

Figure 4 Comparison of the glucose (A) and NEFA (B) immediately after exercise (immediately),

post-15 minutes, post-30 minutes into recovery Two-way analysis of variance (condition 3 time) with repeated

measurements of the second factor.

When analyzing the inflammatory responses, neither

condition affected the IL-6 or TNF-a concentrations Lira

et al (6) analyzed 4 repeated efforts of high intensity

(Wing-ate test) for upper and lower limbs in judo athletes and did

not find significant changes in IL-6 and TNF-a The absence

of change in IL-6 and TNF-a in the present study and Lira

et al (6) may be attributed, in part, to low exercise volumes

Thus, it seems that IL-6 increase is dependent on exercise

volume since we found that IL-6 was enhanced after a similar

exhaustive protocol at 70% of 1RM (2,13) Muscle-derived

IL-6 exerts both a metabolic and immunological effect,

increasing glucose uptake and anti-inflammatory function,

and decreasing TNF-a concentration (11) Steensberg

et al (14) tested if infusion of plasma IL-6 induces an

anti-inflammatory status in young, healthy individuals and did

not observe enhanced levels of the proinflammatory

cyto-kine (TNF-a) but did observe increased plasma levels of

anti-inflammatory cytokines (IL-1 receptor agonist [IL-1ra]

and IL-10) compared with saline infusion The same study

also found IL-6 induced an increase in cortisol Given the

low volume in both conditions (30 and 90 seconds) and high

intensity (90% of 1RM), there may not have sufficient

vol-ume to stimulate IL-6 in this study compared with the

high-er volumes used in our 70% study This may also explain the

difference in the glucose response observed between studies

Contrary to our previous findings (13) that used 4 sets at

70% of 1RM performed until exhaustion with the same

interval recovery as in this study (90- against 30-second),

the 30-second condition exhibited greater glucose levels

than 90-second The anaerobic metabolic pathways of

phos-phocreatine (ATP-CP) and glycolysis are predominantly

used to support the contractile activity of the muscles in this

type of exercise; however, short intervals of recovery do not

provide sufficient time for complete creatine phosphate

re-synthesis leading to a higher glycolytic contribution,

eleva-tions in intracellular [H+], and great utilization of glycogen

stores, stimulating its liberation

Moderate rest intervals (90-second) increased IL-10 and

IL-10/TNF-a ratio after 30 minutes when compared with

pre-exercise values These results disagree with our previous

findings because no difference was found in 10 and

IL-10/TNF-a ratio (13) Izquierdo et al (3) demonstrated IL-10

concentrations increased following 5 sets until movement

failure to 10 RM with 120 seconds of rest between the sets

in male subjects when compared with pretraining condition

Because the 90-second condition performed a higher

exer-cise volume than 30-second (Figure 2), the higher metabolic

demand during the exercise session likely influenced the

IL-10 response (2)

Currently, the IL-10/TNF-a ratio has been adopted as an

inflammatory status indicator, and low levels are associated

with poor prognoses and increased susceptibility to various

morbidities (4,5) Nikseresht et al (8) compared the changes

of this ratio in obese subjects after 12 weeks of training using

high-intensity intermittent exercise (treadmill, 43 4 minute;

80–90% of maximum heart rate) and strength training with nonlinear periodization (40–65 minutes, 3 3 week; mild, moderate, and severe) They showed that a significant increase in the IL-10/TNF-a ratio was accompanied by significant reductions in fat mass and serum insulin concen-trations and also improved the sensitivity to insulin’s action (HOMA-IR) Our group recently found that 4 sets of 70% 1RM with 30-second and 90-second recovery did not increase IL-10 concentrations or the IL-10/TNF-a ratio (13) This may reflect that within high-intensity exercise (90% of 1RM) and moderate recovery interval (90-second), there is an increased anti-inflammatory response The higher IL-10 concentration blocks the possible effects of TNF-a, whereas the IL-10/TNF-a ratio is increased more in the trained subject compared with the sedentary subject (7) This regulation favors the anti-inflammatory environment, and it can be one of the mechanisms through which chronic exercise increases anti-inflammatory response

Although the present study adds data regarding the anti-inflammatory response (higher IL-10 levels and IL-10/ TNF-a ratio) during heavy strength exercise, some limita-tions in this study should be considered, such as the volume discrepancy between conditions It is possible that if repeti-tion volume was the same, the immunometabolic response would be also similar; however, this is yet to be tested Fur-ther research should evaluate the effects of short and mod-erate rest intervals on the immunometabolic response when the volume is matched between conditions

In summary, differing rest intervals promotes diverging immunometabolic responses in recreational weightlifters, with 90-second promoting an anti-inflammatory environ-ment More research is needed to investigate the interaction between heavy chronic training, the immunological response, and adaptation

PRACTICALAPPLICATIONS

This study demonstrates to coaches and trainers who employ heavy strength exercise that moderate recovery intervals between sets promote an increased anti-inflammatory response (IL-10 and IL-10/TNF-a), and together with a higher overall volume achieved may better promote the hypertrophic and adaptive process when train-ing with heavy loads

Fabio Santos Lira thanks Fapesp for their support (2013/ 25310–2) The authors declare that they have no conflict of interest

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