High-Intensity Interval Training Combined with Different Types of Exercises on Cardiac Autonomic Function. An Analytical Cross-Sectional Study in CrossFit® Athletes.

It is well established that endurance exercise has positive effects on cardiac autonomic function (CAF). However, there is still a dearth of information about the effects of regular high-intensity interval training combined with different types of exercises (HIITCE) on CAF. OBJECTIVE: The aim of this study is to compare CAF at rest, its reactivity, and reactivation following maximal exercise testing in HIITCE and endurance athletes. METHODS: An observational study was conducted with 34 male athletes of HIITCE (i.e., CrossFit®) [HG: n = 18; 30.6 ± 4.8 years] and endurance athletes (i.e., triathlon) [TG.: n = 16; 32.8 ± 3.6 years]. We analyzed 5 min of frequency-domain indices (TP, LF, HF, LFn, HFn, and LF/HF ratio) of heart rate variability (HRV) in both supine and orthostatic positions and its reactivity after the active orthostatic test. Post-exercise heart rate recovery (HRR) was assessed at 60, 180, and 300 s. Statistical analysis employed a non-parametric test with a p-value set at 5%. RESULTS: The HG showed reduced HFn and increased LFn modulations at rest (supine). Overall cardiac autonomic modulation (TP) at supine and all indices of HRV at the orthostatic position were similar between groups. Following the orthostatic test, the HG showed low reactivity for all HRV indices compared to TG. After the exercise, HRR does not show a difference between groups at 60 s. However, at 180 and 300 s, an impairment of HRR was observed in HG than in TG. CONCLUSION: At rest (supine), the HG showed reduced parasympathetic and increased sympathetic modulation, low reactivity after postural change, and impaired HRR compared to TG.

Is a short-stage protocol during an incremental exercise test reliable for heart rate variability threshold analysis?

Aim: Heart rate variability threshold (HRVT) is a valid method to determine parasympathetic depression during an incremental exercise test (IET). However, HRVT is usually assessed using the last 60s of each 180s stage of an IET, resulting in longer and demotivating tests. This study aimed to evaluate the agreement of HRVT analysis adopting the first and second minute of R-R interval (iRR) segment comparatively to a standard third-minute segment obtained at each 3-min stage on IET. Methods: Seventeen young male subjects (22.2 ± 3.1 years; 23.4 ± 2.3 kg/m2) underwent IET on a cycle ergometer. HRVT was considered the load corresponding to the point of stabilization of the SD1 index (HRVTV), or the first load with SD1 value < 3ms (HRVT<3), both assessed by the 1st (HRVT1V, HRVT1<3), 2nd (HRVT2V, HRVT2<3) and standard 3rd (HRVT3V, HRVT3<3) 60s iRR segment analyzed at each stage of IET. Agreement and reliability were assessed by the Bland-Altman analysis and the intraclass correlation coefficient (ICC), respectively. Results: High reliability and non-significant bias were observed considering HRVT1V vs HRVT3V (ICC = 0.92; p = 0.18) or HRVT2V vs HRVT3V (ICC = 0.94; p = 0.99). However, lower reliability was observed for HRVT1<3 vs HRVT3<3 (ICC = 0.79; p = 0.75) and for HRVT2<3 vs HRVT3<3 (ICC = 0.91; p = 0.33). Conclusion: HRVT can be similarly assessed by the 1st, 2nd or 3rd 60 seconds iRR segment, mainly when assessed by a visual method.(AU)

Application of Pilates principles increases paraspinal muscle activation.

OBJECTIVE: To analyze the effect of Pilates principles on the EMG activity of abdominal and paraspinal muscles on stable and unstable surfaces. METHODS: Surface EMG data about the rectus abdominis (RA), iliocostalis (IL) and lumbar multifidus (MU) of 19 participants were collected while performing three repetitions of a crunch exercise in the following conditions: 1) with no Pilates technique and stable surface (nP + S); 2) with no Pilates technique and unstable surface (nP + U); 3) with Pilates technique and stable surface (P + S); 4) with Pilates and unstable surface (P + U). The EMG Fanalysis was conducted using a custom-made Matlab(®) 10. RESULTS: There was no condition effect in the RA iEMG with stable and unstable surfaces (F(1,290) = 0 p = 0.98) and with and without principles (F(1,290) = 1.2 p = 0.27). IL iEMG was higher for the stable surface condition (F(1,290) = 32.3 p < 0.001) with Pilates principles (F(1,290) = 21.9 p < 0.001). The MU iEMG was higher for the stable surface condition with and without Pilates principles (F(1,290) = 84.9 p < 0.001).

Effects of resistance exercise versus combined training on post-exercise hypotension in women with metabolic syndrome / Efeitos do exercício de força versus combinado sobre a hipotensão pós-exercício em mulheres com síndrome metabólica

The aim of the present study was to analyze the response of systolic (SBP) and diastolic (DBP) blood following three experimental sessions: resistance exercise (RE), combined exercise (COMB-aerobic and RE) and control session (CON). Thirty women with metabolic syndrome (MS) were randomly assigned to one of three experimental groups: RE (n=10; 36.1 ± 9.0 years) (3 sets of 8-12 repetitions at 80% of 10RM in six exercises for whole body); COMB (n=10; 33.1 ± 5.0 years) (30 min of aerobic exercise at 65-70% of reserve heart rate which was followed by the same RE session) and CON (n=10; 30.4 ± 6.6 years). The SBP and DBP were measured before and every 15 min during 60 min following the experimental sessions. The COMB group presented greater delta SBP (ΔSBP) decrease at 15, 30 and 45 min post-exercise as compared with CON group (p <0.05); the RE group presented greater ΔSBP reduction at 30 and 45 min post-exercise also compared with CON group (p <0.05). In addition, the area under the curve of ΔSBP for COMB group (~30 mmHg of hypotension during 60 min, p ≤ 0.0005) and RE group (~19 mmHg of hypotension during 60 min, p = 0.024) were greater than the CON group. Therefore, RE and COMB elicited post-exercise hypotension in women with MS; COMB provided a greater decrease which may be of value in the prevention and treatment of cardiovascular disorders.

O objetivo do presente estudo foi analisar as respostas de pressão arterial sistólica (PAS) e pressão arterial diastólica (PAD) após três sessões experimentais: exercício de força (EF), exercício combinado (COMB-aeróbio e EF) e controle sem exercício (CON). Trinta mulheres com síndrome metabólica (SM) foram randomicamente alocadas a uma das três sessões experimentais: EF (n=10; 36,1 ± 9,0 anos) (3 séries de 8-12 repetições a 80% de 10RM em 6 exercícios para o corpo todo); COMB (n=10; 33,1 ± 5,0 anos) (30 min de exercício aeróbio a 65-70% da frequência cardíaca de reserva, sucedido da mesma sessão de EF) e CON (n=10; 30,4 ± 6,6 anos). A PAS e PAD foram medidas antes e a cada 15 min, nos 60 min subsequentes às sessões experimentais. O grupo COMB apresentou maior diminuição do delta da PAS (ΔPAS), nos momentos 15, 30 e 45 min pós-exercício, quando comparado ao grupo CON (p <0,05); o grupo EF apresentou maior redução ΔPAS (p < 0,05), nos momentos 30 e 45 minutos pós-exercício, também comparado ao grupo CON. Adicionalmente, a área abaixo da curva do ΔPAS para os grupos COMB (~30 mmHg de hipotensão em 60 min, p ≤ 0,0005) e EF (~19 mmHg de hipotensão em 60 min, p = 0,024) foram maiores em relação ao grupo CON. Portanto, tanto o EF como o COMB induziram hipotensão pós-exercício em mulheres com SM, com maior magnitude para o grupo COMB, o que pode ser interessante para prevenção e tratamento de problemas cardiovasculares.

Sustained effect of resistance training on blood pressure and hand grip strength following a detraining period in elderly hypertensive women: a pilot study.

INTRODUCTION: Hypertension is the most prevalent modifiable risk factor with a high prevalence among older adults. Exercise is a nonpharmacological treatment shown to benefit all patients with hypertension. OBJECTIVE: This study examined the effects of a 14-week moderate intensity resistance training program (RT) on the maintenance of blood pressure and hand grip strength during an extended detraining period in elderly hypertensive women. METHODS: Twelve hypertensive sedentary elderly women completed 14 weeks of whole body RT at a moderate perceived exertion following a detraining period of 14 weeks. RESULTS: Following the training period, participants demonstrated an increase in absolute hand grip strength (P=0.001), relative hand grip strength (P=0.032) and a decrease of systolic (P=0.001), diastolic (P=0.008), and mean blood pressure (P=0.002) when compared to pre-exercise values. In addition, these effects were sustained after 14 weeks of detraining. CONCLUSION: Resistance training may be a valuable method to improve muscular strength and blood pressure in elderly people with benefits being maintained up to 14 weeks following training cessation.

Provável reserva neurofisiológica na execução de exercícios aeróbios máximos / Probable reserves neurophysiological in the execution of maximum aerobic exercises

O modelo tradicional de fisiologia do exercício assume que existe um limite periférico (muscular) em todo exercício aeróbio máximo, devido à hipóxia severa causada pela oferta inadequada de oxigênio ao músculo esquelético. Este evento seria coincidente com o recrutamento de todas as unidades motoras disponíveis no músculo ativo, no mesmo instante. Entretanto, evidências recentes não se ajustam a estas predições. Pelo contrário, um modelo de regulação central do esforço defende a existência de reserva neurofisiológica em todo exercício aeróbio máximo. Nessa nova interpretação, o sistema nervoso central (SNC) modularia o recrutamento muscular para impedir a ativação de todas as unidades motoras ao mesmo tempo, e evitar o excesso de dano à matriz celular. Tal modulação realizada pelo SNC seria um mecanismo natural de defesa do organismo contra a falha catastrófica e o rigor mortis. Alguns resultados obtidos pelo Grupo de Estudo em Psicofisiologia do Exercício poderiam ser interpretados de acordo com a presença de uma reserva neurofisiológica, pois a potência mecânica máxima (WMAX) num teste incremental máximo foi aumentada após ingestão de cafeína e placebo percebido como cafeína, porém, sem alteração no consumo máximo de oxigênio (VO2MAX), sugerindo não haver limitação periférica. Entretanto, estudos devem ser desenhados para responder essa questão de forma mais consistente, incluindo medidas metabólicas e de excitabilidade dos músculos esqueléticos, mas também do SNC, durante exercício.

The traditional model of exercise physiology assumes that there would be a peripheral (muscular) limit in maximal aerobic exercises due to severe hypoxia derived from inadequate oxygen supply to the skeletal muscles. This event is to be coincident with the total recruitment of available motor units in the active muscles. However, recent evidence does not agree with these predictions. Rather, a centrally-regulated effort model argues that there is a neurophysiological reserve in all maximal aerobic exercises. In this new interpretation the central nervous system (CNS) would modulate the muscle recruitment to prevent the recruitment of all available motor units at the same time in order to avoid excessive harm in cellular matrixes. Such modulation performed by the CNS would be a natural mechanism to defend the body against catastrophic failure and rigor mortis. Some results obtained by the Exercise Psychophysiology Research Group may be interpreted according to this neurophysiological reserve as the peak power output (WPEAK) in a maximum incremental test was increased after caffeine and placebo perceived as caffeine ingestion, but without change in maximal oxygen consumption (VO2MAX), suggesting no peripheral limitation. Yet, studies including measures of metabolic and skeletal muscle excitability in addition to the CNS function during exercise may answer this question closer.

The interactions between hemostasis and resistance training: a review.

Physical inactivity is considered a risk factor for cardiovascular disease and is strongly associated with changes in arterial structure. Regular physical activity and exercise contributes to the prevention of coronary artery disease. Therefore, cardiovascular and resistance training improve hemostatic parameters and promote a less thrombotic blood profile. This review highlights the studies, mechanisms, and outcomes relating to the effectiveness of resistance training on the process of hemostasis. The Pubmed, Scopus, Medline, Scielo, Lilacs, Ibecs, and Cochrane databases were used to locate the original articles. Seventeen studies were found during the research process. Of these, ten articles were excluded. Those protocols using a high volume of training for young adults showed a greater fibrinolytic response, and training protocols with intensities above 80% of 1 maximum repetition showed an increased platelet activity. In subjects with coronary artery disease, just one session of resistance training resulted in improvement in the fibrinolytic system (tissue plasminogen activator) without raising potential thrombotic markers.

Construção e calibração de uma bicicleta de ciclismo indoor com graduação de carga / Deveopment and calibration of an indoor cycling bicycle with load graduation

Tem havido uma grande busca pela modalidade de Ciclismo Indoor (CI) em academias, o que se deve ao êxodo dos praticantes de ciclismo de rua em prol de segurança, treinamento e praticidade, além do interesse pelo potencial do CI nos processos de emagrecimento e condicionamento cardiovascular. Há poucos estudos nessa área, dentre as principais causas, está à limitação da bicicleta de ciclismo indoor (BCI) que não quantifica a carga utilizada e da potência produzida. Isto tem dificultado a avaliação funcional e a prescrição adequada de treinamento. Assim, a solução é implementar a uma BCI um sistema de carga. O objetivo do estudo foi construir e calibrar uma BCI que gradue a carga utilizada e a potência produzida. A metodologia foi dividida em quatro etapas: 1) fundamentação teórica; 2) desenvolvimento do protótipo; 3) construção; e 4) calibração. O projeto baseou-se na adaptação, em uma BCI, de um sistema de carga do ciclo ergômetro de frenagem mecânica Monark (cesto de anilha), que mensura tais variáveis e é tido como padrão ouro. Considerações finais: a BCI por ter respeitado os fundamentos básicos do modelo de referência, por ter sido construída com materiais novos e pela manutenção das dimensões do circuito Roda-Volante/Coroa/Catraca padrão Monark, parecem impedir qualquer tipo de limitação para a possível validade de constructo do protótipo, além de ter baixo custo. Portanto, a BCI construída, por possibilitar a graduação de carga e a potência produzida, pode ser classificada como um cicloergômetro, além do que, sua geometria, fiel às características das bicicletas de CI, acabou por preencher uma lacuna existente nesta área...

Indoor Cycling (IC) has considerably grown at fitness centers, due to practitioners giving-up of street cycling because of security issues as well as the trainability and practicity. IC also has the potencial for helping to lose weight and cardiovascular conditioning. There are only few studies on this subject, and the main reason is the limitation of the Indoor Cycling Bicycle (ICB), which does not either measure work load or power. Therefore, functional evaluation and adequate training prescription are limited and the solution lies on implementation of an ICB with loading system. This paper has the purpose of describing the development and calibration of an ICB that actually measures workload and power. The project was based on the adaptation of a loading system from a Monark mechanical lockwire cycloergometer (basket of weight), which measurement is considered a gold standard, on an ICB. The adaptation, for having maintaining the Monark dimensions of the Flywheel/Crown/Ratchet circuit as well as for using new materials, seems not to offer any type of limitation for prototype construct validity. The ICB also had a low cost. Therefore, this ICB can be classified as a cycloergometer. The adaptation permited to advance in this area, by both maintaining orignal ICB characteristics and also controlling for workload and power...

Prevençäo de lesöes no ciclismo indoor - uma proposta metodológica / Prevention of injuries indoor cycling - a methodological proposal

Este estudo teve como objetivo apresentar uma proposta metodológica para a prevençäo de lesöes no Ciclismo Indoor (CI) em bicicleta estacionária. Nesse sentido, buscou-se, a partir da fundamentaçäo teórica, conceituaçöes da modalidade, dos equipamentos e lesöes. Na seqüência, säo apresentadas as condutas dos profissionais da área de saúde em relaçäo à problemática da prevençäo das principais lesöes. Ao final säo apresentadas, de forma hierárquica, as condutas preventivas.