Effects of sprint interval exercise dose and sex on circulating irisin and redox status markers in adolescent swimmers

Comparison of Ultra-Short Race Pace and High-Intensity Interval Training in Age Group Competitive Swimmers

The aim of this study was tο examine the acute responses to an Ultra-Short Race Pace Training (USRPT) and a High-Intensity Interval Training (HIIT), both oriented for the event of 100 m freestyle. Eighteen national-level swimmers (8 boys, 10 girls) aged 13.5 ± 0.1 years, with 8.0 ± 0.5 years of experience participated in the study. All participants completed a USRPT and a HIIT protocol consisting of 2 × 10 × 25 m (USRPT1 & USRPT2) and 5 × 50 m. Significantly higher swimming velocity (SV) were achieved in USRPT compared to HIIT (p < 0.001), while significantly lower distance per stroke (DPS) and stroke index (SI) were obtained (p = 0.007 and p < 0.001). Also, significantly lower blood lactate and glucose (BL & BG) concentrations were found after USRPT (p ≤ 0.001 and p = 0.037). Heart rate (HR) and rate of perceived exertion (RPE) were significantly lower after USRPT than HIIT (p < 0.001 and p = 0.015). According to the results, an USRPT swimming set consisting of 20 × 25 m at a 100 m pace seems to induce more specific responses in kinematic characteristics, biomarkers, HR and RPE compared to a 5 × 50 m HIIT set.

Irisin: A bridge between exercise and neurological diseases

Exercise plays a beneficial regulating role on each organ of the body through different mechanisms and is a powerful weapon to prevent disease. Irisin is released from muscle and widely distributed in the human body, participating in the physiological processes of multiple human systems and playing a protective role in multiple human organs. The protective effect of irisin on the nervous system is particularly remarkable, which can improve cognitive function, reduce the risk of ischemic stroke and improve its prognosis. Irisin also plays a guiding role in the prevention and treatment of neurodegenerative diseases and ischemic cerebrovascular diseases. Exercise is the driving factor promoting irisin secretion, and different exercise modes, intensity, frequency, and time all affect the level of serum irisin. As a result of analyzing the effects of various exercise modes on irisin secretion, we proposed an exercise program with a higher level of irisin secretion.

Low-Volume Sprint Interval Swimming Is Sufficient to Increase Blood Metabolic Biomarkers in Master Swimmers

Purpose: Sprint interval exercise is a time-efficient way of inducing beneficial adaptations. However, little is known about its minimal effective volume, especially in swimming. The aim of the present study was to evaluate and compare the effects of two sprint interval swimming sets of different low volumes on blood biomarkers. Method: Twenty-one master swimmers [11 females aged 38.5 (8.5) years, 10 males aged 42.7 (5.7) years] completed two freestyle swimming sets of 4 × 50 m and 4 × 25 m at maximal intensity and a work-to-rest ratio of 1:1, on different days, in random and counterbalanced order. Blood samples were taken before, immediately after and one hour after exercise for determination of a number of biochemical parameters. Results: Swimming speed was higher in the 4 × 25-m set. Lactate, glucose, insulin, glucagon, cortisol, and reduced glutathione increased immediately post-exercise, while uric acid increased 1 h post-exercise (p < .05). All aforementioned biomarkers, excluding glucagon, increased more with the 4 × 50-m set, compared to the 4 × 25-m set (p < .05). Session rating of perceived exertion was higher after the 4 × 50-m set (p = .011). Conclusion: Both sprint interval swimming sets elicited increases in blood biomarkers in master swimmers. The set of higher volume elicited greater increases in most of the biochemical markers studied but also in subjective load. Thus, although the set of higher volume was more efficient in perturbing blood biomarkers, even the very low-volume set induced metabolic stress that may trigger adaptive mechanisms.

Relevance of a Sprint Interval Swim Training Set to the 100-Meter Freestyle Event Based on Blood Lactate and Kinematic Variables

Sprint interval training (SIT) sets are commonly used by coaches in the training routine of swimmers competing in short-distance events; however, data regarding their relevance to competitive events are scarce. The aim of this study was to examine whether performance variables differed or correlated between a 4 × 50-m maximal swimming set (with a work-to-rest ratio of 1:4) and the 100-m freestyle event. Eleven male and 16 female competitive swimmers aged 16.1 ± 1.1 years participated in the study. All swimmers trained at least six times a week and had training experience of more than 4 years. They completed the two freestyle tests on different days, in random and counterbalanced order. In each test, speed, blood lactate, stroke rate (SR), and stroke index (SI) were measured. Speed, blood lactate, and SR were higher at the 4 × 50 m compared to the 100 m and were positively correlated between tests (p < 0.001). The SI did not differ significantly, but was positively correlated between tests. Males were faster and had a higher SI than females, but genders did not differ in lactate. Since performance variables were better in the SIT set and correlated with those in the 100-m bout, we suggest that the 4 × 50-m set can be used to improve performance in the 100-m freestyle event. Moreover, this set can help coaches identify which swimmers will swim fastest in the event.

Changes in Inflammatory Cytokines and Irisin in Response to High Intensity Swimming in Adolescent versus Adult Male Swimmers

Swimming is a popular youth sport that is considered beneficial for cardiovascular fitness. However, the potential inflammatory outcomes of high intensity swimming in younger swimmers are unclear, as is the response of irisin, a myokine released during exercise with anti-inflammatory properties. This study compared the plasma concentrations of interleukins 1-beta (IL-1β), 6 (IL-6), 10 (IL-10), tumor necrosis factor alpha (TNF-α) and irisin in response to intense swimming between adolescent and adult male swimmers. Thirty-two swimmers (16 adolescents, 14 ± 1 years; 16 adults, 21.5 ± 3.1 years) completed a high intensity interval swimming trial. At rest, only TNF-α was higher (33%, p < 0.05) in adolescents compared with adults. There was an overall significant increase in IL-1β from pre- to post-swimming (3% in adolescents, 24% in adults), but no significant interaction. IL-10 significantly increased in both groups (+34% in adolescents, +56% in adults). IL-6 and TNF-α increased significantly (+32% and +26%, respectively) in adults, but not in adolescents (+2% and -9%, respectively). Adults showed a small, but significant decrease in irisin (-5%), with no change in adolescents. The lack of an IL-6, TNF-α and irisin response to intense swimming in adolescent swimmers may suggest a blunted inflammatory and myokine response following high intensity exercise in trained youth.

Response of Blood Biomarkers to Sprint Interval Swimming

PURPOSE

To evaluate and compare the effects of 2 sprint interval training (SIT) sets of different distances on biochemical markers indicative of metabolism, stress, and antioxidant capacity in competitive swimmers and, to investigate the potential influence of gender on these markers.

METHODS

Twenty-four adolescent, well-trained swimmers (12 men and 12 women) participated in the study. In a random and counterbalanced order, the swimmers completed 2 SIT sets (8 × 50 m and 8 × 25 m) in freestyle with maximal intensity on different days. Work-to-rest ratio was 1:1 in both sets. Blood samples were drawn preexercise, immediately postexercise, and 1 hour postexercise to evaluate the effects of the SIT sets on a number of biochemical parameters.

RESULTS

Swimming speed was higher at 8 × 25 m. The 2 SIT sets induced significant increases in lactate, glucose, insulin, glucagon, cortisol, and uric acid (P ≤ .001). No differences in these parameters were found between sets, except for irisin (higher in 8 × 50 m; P = .02). Male swimmers were faster and had higher lactate and uric acid concentrations, as well as lower reduced glutathione concentration, than female swimmers (P < .01).

CONCLUSIONS

The 2 swimming SIT sets induced increases in most of the biochemical markers studied. The 2-fold difference between sets in distance did not differentiate the effects of sprint interval exercise on most biochemical parameters. Thus, low-volume SIT sets seem to be effective stimuli for competitive swimmers.

Redox Homeostasis and Inflammation Responses to Training in Adolescent Athletes: a Systematic Review and Meta-analysis

Background

Several studies have highlighted the substantial role of the athlete’s redox and inflammation status during the training process. However, many factors such as differences in testing protocols, assays, sample sizes, and fitness levels of the population are affecting findings and the understanding regarding how exercise affects related biomarkers in adolescent athletes.

Objectives

To search redox homeostasis variables’ and inflammatory mediators’ responses in juvenile athletes following short- or long-term training periods and examine the effect size of those variations to training paradigms.

Methods

A PRISMA-compliant systematic review and meta-analysis were conducted. The entire content of PubMed (MEDLINE), Scopus, and Science Direct were systematically searched until December 2019. Studies with outcomes including (1) a group of adolescent athletes from any individual or team sport, (2) the assessment of redox and/or inflammatory markers after a short- (training session or performance testing) or longer training period, and (3) variables measured in blood were retained. The literature search initially identified 346 potentially relevant records, of which 36 studies met the inclusion criteria for the qualitative synthesis. From those articles, 27 were included in the quantitative analysis (meta-analysis) as their results could be converted into common units.

Results

Following a short training session or performance test, an extremely large increase in protein carbonyls (PC) (ES 4.164; 95% CI 1.716 to 6.613; Z = 3.333, p = 0.001), a large increase in thiobarbituric acid reactive substances (TBARS) (ES 1.317; 95% CI 0.522 to 2.112; Z = 3.247, p = 0.001), a large decrease in glutathione (GSH) (ES − 1.701; 95% CI − 2.698 to − 0.705; Z = − 3.347, p = 0.001), and a moderate increase of total antioxidant capacity (TAC) level (ES 1.057; 95% CI − 0.044 to 2.158; Z = 1.882, p = 0.060) were observed. Following more extended training periods, GSH showed moderate increases (ES 1.131; 95% CI 0.350 to 1.913; Z = 2.839, p = 0.005) while TBARS displayed a small decrease (ES 0.568; 95% CI − 0.062 to 1.197; Z = 1.768, p = 0.077). Regarding cytokines, a very large and large increase were observed in IL-6 (ES 2.291; 95% CI 1.082 to 3.501; Z = 3.713, p = 0.000) and IL-1 receptor antagonist (ra) (ES 1.599; 95% CI 0.347 to 2.851; Z = 2.503, p = 0.012), respectively, following short-duration training modalities in juvenile athletes.

Conclusions

The results showed significant alterations in oxidative stress and cytokine levels after acute exercise, ranging from moderate to extremely large. In contrast, the variations after chronic exercise ranged from trivial to moderate. However, the observed publication bias and high heterogeneity in specific meta-analysis advocate the need for further exploration and consistency when we deal with the assessed variables to ascertain the implications of structured training regimes on measured variables in order to develop guidelines for training, nutritional advice, and wellbeing in young athletes.

Trial Registration

PROSPERO CRD42020152105

Irisin and markers of metabolic derangement in non-diabetic Caucasian subjects with stage I-II obesity during early aging

Irisin concentrations are decreased in subjects with overt diabetes and upregulated in those with obesity or impaired fasting glucose. However, gender-balanced data in older populations, in whom risk factors commonly culminate in overt cardiovascular disease, are scarce. We assessed in non-diabetic Caucasian subjects with stage I-II obesity in the early aging range (50 to 70 years), the relationship between irisin, body composition and markers of metabolic derangement by gender. In 60 (31 women, 29 men) non-diabetics with a body mass index ≥30 - ≤40 kg/m², we measured anthropometrics and body composition (Air Displacement Plethysmography). We assayed lipid and glucose profile by routine methods, plasma irisin by ELISA and measured insulin resistance by the HOMA index. Irisin levels were higher in women than in men (161 [105–198]) vs 83 [33–115] ng/ml, P<0.001), and correlated directly with HOMA index in both (rho 0.735, P<0.001 M, rho 0.452, P = 0.011 F). Sex differences were maintained across insulin resistance severity stages. In men, irisin concentrations correlated directly with body mass index (rho 0.755, P<0.001), waist circumference (rho 0.623, P<0.001), fat mass index (rho 0.762, P<0.001), glucose (rho 0.408, P = 0.028), the fatty liver index (rho 0.705, P<0.001) and FINDRISC score (rho 0.536, P = 0.003). Among non-diabetic Caucasian subjects with obesity in the early stages of aging, irisin levels reflect the amount of body fat and insulin resistance severity, independently of between-gender differences in the adipomyokine concentrations and are associated with markers of visceral adiposity in men but not in women.

Interventions targeted at oxidatively generated modifications of nucleic acids focused on urine and plasma markers

Oxidative stress is associated with the development and progression of numerous diseases. However, targeting oxidative stress has not been established in the clinical management of any disease. Several methods and markers are available to measure oxidative stress, including direct measurement of free radicals, antioxidants, redox balance, and oxidative modifications of cellular macromolecules. Oxidatively generated nucleic acid modifications have attracted much interest due to the pre-mutagenic oxidative modification of DNA into 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), associated with cancer development. During the last decade, the perception of RNA has changed from that of a 'silent messenger' to an 'active contributor', and, parallelly oxidatively generated RNA modifications measured as 8-oxo-7,8-dihydro-guanosine (8-oxoGuo), has been demonstrated as a prognostic factor for all-caused and cardiovascular related mortality in patients with type 2 diabetes. Several attempts have been made to modify the amount of oxidative nucleic acid modifications. Thus, this review aims to introduce researchers to the measurement of oxidatively generated nucleic acid modifications as well as critically review previous attempts and provide future directions for targeting oxidatively generated nucleic acid modifications.