Breathing Monitoring in Soccer: Part I-Validity of Commercial Wearable Sensors.

Growing evidence suggests that respiratory frequency (fR) is a valid marker of effort during high-intensity exercise, including sports of an intermittent nature, like soccer. However, very few attempts have been made so far to monitor fR in soccer with unobtrusive devices. This study assessed the validity of three strain-based commercial wearable devices measuring fR during soccer-specific movements. On two separate visits to the soccer pitch, 15 players performed a 30 min validation protocol wearing either a ComfTech® (CT) vest or a BioharnessTM (BH) 3.0 strap and a Tyme WearTM (TW) vest. fR was extracted from the respiratory waveform of the three commercial devices with custom-made algorithms and compared with that recorded with a reference face mask. The fR time course of the commercial devices generally resembled that of the reference system. The mean absolute percentage error was, on average, 7.03% for CT, 8.65% for TW, and 14.60% for BH for the breath-by-breath comparison and 1.85% for CT, 3.27% for TW, and 7.30% for BH when comparison with the reference system was made in 30 s windows. Despite the challenging measurement scenario, our findings show that some of the currently available wearable sensors are indeed suitable to unobtrusively measure fR in soccer.

Sustained increase in physical fitness independently predicts improvements in cardiometabolic risk profile in type 2 diabetes.

AIMS: To investigate the relationship between changes in physical fitness and cardiovascular risk factors and scores in patients with type 2 diabetes receiving either a behavioural counselling intervention to increase moderate-to-vigorous-intensity physical activity (MVPA) and decrease sedentary-time (SED-time) or standard care. MATERIALS AND METHODS: This is a pre-specified ancillary analysis of the Italian Diabetes and Exercise Study_2, a 3-year randomized clinical trial in which 300 physically inactive and sedentary patients were randomized 1:1 to receive either a one-month theoretical and practical counselling each year or standard care. Mean changes from baseline throughout the 3-year period in MVPA, SED-time, cardiorespiratory fitness (VO2max ), muscle strength, flexibility, cardiovascular risk factors and scores were calculated for study completers (n = 267) and considered irrespective of study arm. RESULTS: Haemoglobin (Hb) A1c and coronary heart disease (CHD) risk scores decreased with quartiles of VO2max and lower body muscle strength changes. Multivariable linear regression analysis showed that increases in VO2max independently predicted decreases in HbA1c , blood glucose, diastolic blood pressure (BP), CHD and total stroke 10-year risk and increases in HDL cholesterol, whereas increases in lower body muscle strength independently predicted decreases in body mass index (BMI), waist circumference, triglycerides, systolic BP, CHD and fatal stroke 10-year risk. These associations remained after including changes in BMI, waist circumference, fat mass and fat-free mass, or MVPA and SED-time as covariates. CONCLUSIONS: Improvement in physical fitness predicts favourable changes in cardiometabolic risk profile, independent of changes not only in (central) adiposity or body composition but also in MVPA and SED-time. TRIAL REGISTRATION: ClinicalTrials.gov; NCT01600937; URL https://clinicaltrials.gov/ct2/show/NCT01600937.

Differential control of respiratory frequency and tidal volume during exercise.

The lack of a testable model explaining how ventilation is regulated in different exercise conditions has been repeatedly acknowledged in the field of exercise physiology. Yet, this issue contrasts with the abundance of insightful findings produced over the last century and calls for the adoption of new integrative perspectives. In this review, we provide a methodological approach supporting the importance of producing a set of evidence by evaluating different studies together-especially those conducted in 'real' exercise conditions-instead of single studies separately. We show how the collective assessment of findings from three domains and three levels of observation support the development of a simple model of ventilatory control which proves to be effective in different exercise protocols, populations and experimental interventions. The main feature of the model is the differential control of respiratory frequency (fR) and tidal volume (VT); fR is primarily modulated by central command (especially during high-intensity exercise) and muscle afferent feedback (especially during moderate exercise) whereas VT by metabolic inputs. Furthermore, VT appears to be fine-tuned based on fR levels to match alveolar ventilation with metabolic requirements in different intensity domains, and even at a breath-by-breath level. This model reconciles the classical neuro-humoral theory with apparently contrasting findings by leveraging on the emerging control properties of the behavioural (i.e. fR) and metabolic (i.e. VT) components of minute ventilation. The integrative approach presented is expected to help in the design and interpretation of future studies on the control of fR and VT during exercise.

How to Investigate the Effect of Music on Breathing during Exercise: Methodology and Tools.

Music is an invaluable tool to improve affective valence during exercise, with the potential contribution of a mechanism called rhythmic entrainment. However, several methodological limitations impair our current understanding of the effect of music on relevant psychophysiological responses to exercise, including breathing variables. This study presents conceptual, methodological, and operational insight favoring the investigation of the effect of music on breathing during exercise. Three tools were developed for the quantification of the presence, degree, and magnitude of music-locomotor, locomotor-breathing, and music-breathing entrainment. The occurrence of entrainment was assessed during 30 min of moderate cycling exercise performed either when listening to music or not, and was complemented by the recording of relevant psychophysiological and mechanical variables. Respiratory frequency and expiratory time were among the physiological variables that were affected to a greater extent by music during exercise, and a significant (p < 0.05) music-breathing entrainment was found in all 12 participants. These findings suggest the importance of evaluating the effect of music on breathing responses to exercise, with potential implications for exercise prescription and adherence, and for the development of wearable devices simultaneously measuring music, locomotor, and breathing signals.

Effects of exercise before and/or after a mixed lunch on postprandial metabolic responses in healthy male individuals.

PURPOSE: Exercise plays an important role in preventing and treating postprandial dysmetabolism. We investigated the postprandial metabolic responses to a standard lunch when a session of aerobic exercise is performed in the early postprandial phase or divided between the pre- and postprandial period. METHODS: Nine healthy volunteers consumed a standardised mixed lunch and rested for the following 3 h (Con) or performed 40 min of cycling at 65% V̇O2max after lunch (CPPEx), or two 20-min sessions, one before (SplitEx1) and the other after lunch (SplitEx2), at the same intensity. RESULTS: At 1-h post-lunch, a significant reduction (P < 0.001) in glycaemia was observed for CPPEx (- 25 ± 10%) and SplitEx (- 34 ± 7%) compared to Con. Yet, a post-exercise rebound lessened the exercise effect on the glycaemic area under the curve (AUC) at 2 and 3 h. At 1 h, a significant reduction (P < 0.009) in plasma insulin (SplitEx - 53 ± 31%; CCPEx - 48 ± 20%) and C-peptide (SplitEx - 57 ± 20%; CCPEx - 47 ± 24%) was observed compared to Con. Glucose-dependent insulinotropic polypeptide (GIP) increased after the meal, without differences between conditions. Compared with SplitEx1, cortisol response was attenuated during SplitEx2 and CPPEx. At 3 hours, triglyceride AUC was significantly higher (P = 0.039) in SplitEx compared to Con (+ 19 ± 8%). CONCLUSION: Forty minutes of postprandial exercise or 20 min of pre- and postprandial exercise are both effective at attenuating the glycaemic and insulinaemic response to a mixed lunch, while a higher lipaemia was found in the pre- and postprandrial exercise condition.

The effect of pedalling cadence on respiratory frequency: passive vs. active exercise of different intensities.

PURPOSE: Pedalling cadence influences respiratory frequency (fR) during exercise, with group III/IV muscle afferents possibly mediating its effect. However, it is unclear how exercise intensity affects the link between cadence and fR. We aimed to test the hypothesis that the effect of cadence on fR is moderated by exercise intensity, with interest in the underlying mechanisms. METHODS: Ten male cyclists performed a preliminary ramp incremental test and three sinusoidal experimental tests on separate visits. The experimental tests consisted of 16 min of sinusoidal variations in cadence between 115 and 55 rpm (sinusoidal period of 4 min) performed during passive exercise (PE), moderate exercise (ME) and heavy exercise (HE). The amplitude (A) and phase lag (φ) of the dependent variables were calculated. RESULTS: During PE, fR changed in proportion to variations in cadence (r = 0.85, P < 0.001; A = 3.9 ± 1.4 breaths·min-1; φ = - 5.3 ± 13.9 degrees). Conversely, the effect of cadence on fR was reduced during ME (r = 0.73, P < 0.001; A = 2.6 ± 1.3 breaths·min-1; φ = - 25.4 ± 26.3 degrees) and even more reduced during HE (r = 0.26, P < 0.001; A = 1.8 ± 1.0 breaths·min-1; φ = - 70.1 ± 44.5 degrees). No entrainment was found in any of the sinusoidal tests. CONCLUSION: The effect of pedalling cadence on fR is moderated by exercise intensity-it decreases with the increase in work rate-and seems to be mediated primarily by group III/IV muscle afferents, at least during passive exercise.

Muscle fatigability in patients with type 2 diabetes: relation with long-term complications.

AIMS: It is unclear whether long-term complications play a role in muscle fatigue characteristic of patients with type 2 diabetes mellitus (T2DM). The purpose of this study was to investigate the association between muscle fatigability and microvascular and macrovascular complications in patients with T2DM. METHODS: One-hundred forty-six patients with T2DM (80 males, 66 females, aged 66.9 ± 7.9 years) were recruited. Maximal voluntary contraction (MCV) and endurance time (ET, 50% of the MVC) were assessed at the knee extensor muscles with an isometric dynamometer. Univariate and multivariate correlations of ET values with diabetic complications, a wide range of surrogate measures of these sequelae, and cardiovascular risk factors were examined. RESULTS: A higher muscle fatigability was detected in patients with diabetic peripheral neuropathy (DPN, ET: -32.4%), cardiovascular disease (CVD, ET: -32.1%), retinopathy (ET: -35.8%), and nephropathy (ET: -30.4%). At univariate analysis, muscle fatigability was associated with age, physical activity level, diabetes duration, HbA1c , systolic blood pressure, albuminuria, eGFR, and several parameters of nervous and vascular function. Multivariate analysis showed that, after adjusting for covariates, ET was independently associated with sensory nerve conduction velocity, vibration perception threshold at malleolus, and ankle-brachial index. In addition, ET values were independently associated with the presence of DPN, CVD, and retinopathy. CONCLUSIONS: In T2DM, muscle fatigability is associated with presence of DPN, CVD, and retinopathy. Such defect appears to be mediated predominantly by sensory nerve and peripheral vascular dysfunction.

The Importance of Respiratory Rate Monitoring: From Healthcare to Sport and Exercise.

Respiratory rate is a fundamental vital sign that is sensitive to different pathological conditions (e.g., adverse cardiac events, pneumonia, and clinical deterioration) and stressors, including emotional stress, cognitive load, heat, cold, physical effort, and exercise-induced fatigue. The sensitivity of respiratory rate to these conditions is superior compared to that of most of the other vital signs, and the abundance of suitable technological solutions measuring respiratory rate has important implications for healthcare, occupational settings, and sport. However, respiratory rate is still too often not routinely monitored in these fields of use. This review presents a multidisciplinary approach to respiratory monitoring, with the aim to improve the development and efficacy of respiratory monitoring services. We have identified thirteen monitoring goals where the use of the respiratory rate is invaluable, and for each of them we have described suitable sensors and techniques to monitor respiratory rate in specific measurement scenarios. We have also provided a physiological rationale corroborating the importance of respiratory rate monitoring and an original multidisciplinary framework for the development of respiratory monitoring services. This review is expected to advance the field of respiratory monitoring and favor synergies between different disciplines to accomplish this goal.

Personalizing physical exercise in a computational model of fuel homeostasis.

The beneficial effects of physical activity for the prevention and management of several chronic diseases are widely recognized. Mathematical modeling of the effects of physical exercise in body metabolism and in particular its influence on the control of glucose homeostasis is of primary importance in the development of eHealth monitoring devices for a personalized medicine. Nonetheless, to date only a few mathematical models have been aiming at this specific purpose. We have developed a whole-body computational model of the effects on metabolic homeostasis of a bout of physical exercise. Built upon an existing model, it allows to detail better both subjects' characteristics and physical exercise, thus determining to a greater extent the dynamics of the hormones and the metabolites considered.

Contact-Based Methods for Measuring Respiratory Rate.

There is an ever-growing demand for measuring respiratory variables during a variety of applications, including monitoring in clinical and occupational settings, and during sporting activities and exercise. Special attention is devoted to the monitoring of respiratory rate because it is a vital sign, which responds to a variety of stressors. There are different methods for measuring respiratory rate, which can be classed as contact-based or contactless. The present paper provides an overview of the currently available contact-based methods for measuring respiratory rate. For these methods, the sensing element (or part of the instrument containing it) is attached to the subject's body. Methods based upon the recording of respiratory airflow, sounds, air temperature, air humidity, air components, chest wall movements, and modulation of the cardiac activity are presented. Working principles, metrological characteristics, and applications in the respiratory monitoring field are presented to explore potential development and applicability for each method.

Effect of a Behavioral Intervention Strategy on Sustained Change in Physical Activity and Sedentary Behavior in Patients With Type 2 Diabetes: The IDES_2 Randomized Clinical Trial.

Importance: There is no definitive evidence that changes in physical activity/sedentary behavior can be maintained long term in individuals with type 2 diabetes. Objective: To investigate whether a behavioral intervention strategy can produce a sustained increase in physical activity and reduction in sedentary time among individuals with type 2 diabetes. Design, Setting, and Participants: The Italian Diabetes and Exercise Study 2 was an open-label, assessor-blinded, randomized clinical superiority trial, with recruitment from October 2012 to February 2014 and follow-up until February 2017. In 3 outpatient diabetes clinics in Rome, 300 physically inactive and sedentary patients with type 2 diabetes were randomized 1:1 (stratified by center, age, and diabetes treatment) to receive a behavioral intervention or standard care for 3 years. Interventions: All participants received usual care targeted to meet American Diabetes Association guideline recommendations. Participants in the behavioral intervention group (n = 150) received 1 individual theoretical counseling session and 8 individual biweekly theoretical and practical counseling sessions each year. Participants in the standard care group (n = 150) received only general physician recommendations. Main Outcomes and Measures: Co-primary end points were sustained change in physical activity volume, time spent in light-intensity and moderate- to vigorous-intensity physical activity, and sedentary time, measured by an accelerometer. Results: Of the 300 randomized participants (mean [SD] age, 61.6 [8.5] years; 116 women [38.7%]), 267 completed the study (133 in the behavioral intervention group and 134 in the standard care group). Median follow-up was 3.0 years. Participants in the behavioral intervention and standard care groups accumulated, respectively, 13.8 vs 10.5 metabolic equivalent-h/wk of physical activity volume (difference, 3.3 [95% CI, 2.2-4.4]; P < .001), 18.9 vs 12.5 min/dof moderate- to vigorous-intensity physical activity (difference, 6.4 [95% CI, 5.0-7.8]; P < .001), 4.6 vs 3.8 h/d of light-intensity physical activity (difference, 0.8 [95% CI, 0.5-1.1]; P < .001), and 10.9 vs 11.7 h/d of sedentary time (difference, -0.8 [95% CI, -1.0 to -0.5]; P < .001). Significant between-group differences were maintained throughout the study, but the between-group difference in moderate- to vigorous-intensity physical activity decreased during the third year from 6.5 to 3.6 min/d. There were 41 adverse events in the behavioral intervention group and 59 in the standard care group outside of the sessions; participants in the behavioral intervention group experienced 30 adverse events during the sessions (most commonly musculoskeletal injury/discomfort and mild hypoglycemia). Conclusions and Relevance: Among patients with type 2 diabetes at 3 diabetes clinics in Rome who were followed up for 3 years, a behavioral intervention strategy compared with standard care resulted in a sustained increase in physical activity and decrease in sedentary time. Further research is needed to assess the generalizability of these findings. Trial Registration: ClinicalTrials.gov Identifier: NCT01600937.

The acute effect of Quercetin on muscle performance following a single resistance training session.

PURPOSE: To examine the effect of acute quercetin (Q) ingestion on neuromuscular function, biomarkers of muscle damage, and rate of perceived exertion (RPE) in response to an acute bout of resistance training. METHODS: 10 young men (22.1 ± 1.8 years, 24.1 ± 3.1 BMI) participated in a randomized, double-blind, crossover study. Subjects consumed Q (1 g/day) or placebo (PLA) 3 h prior to a resistance training session which consisted of 3 sets of 8 repetitions at 80% of the one repetition maximum (1RM) completed bilaterally for eight different resistance exercises. Electromyographic (EMG) signals were recorded from the knee extensor muscles during maximal isometric (MVIC) and isokinetic voluntary contractions, and during an isometric fatiguing test. Mechanical and EMG signals, biomarkers of cell damage, and RPE score were measured PRE, immediately POST, and 24 h (blood indices only) following the resistance exercise. RESULTS: After a single dose of Q, the torque-velocity curve of knee extensors was enhanced and after the resistance exercise, subjects showed a lower MVIC reduction (Q: 0.91 ± 6.10%, PLA: 8.66 ± 5.08%) with a greater rate of torque development (+ 10.6%, p < 0.005) and neuromuscular efficiency ratio (+ 28.2%, p < 0.005). Total volume of the resistance exercises was significantly greater in Q (1691.10 ± 376.71 kg rep) compared to PLA (1663.65 ± 378.85 kg rep) (p < 0.05) with a comparable RPE score. No significant differences were found in blood marker between treatments. CONCLUSIONS: The acute ingestion of Q may enhance the neuromuscular performance during and after a resistance training session.

Muscle fatigability in type 2 diabetes.

BACKGROUND: Patients with type 2 diabetes (T2D) may be subject to premature muscle fatigue. However, the effect of diabetes on muscle fatigability has not yet been thoroughly examined. The purpose of this study was to investigate the effect of T2D on muscle fatigability at the upper and lower body. METHODS: Thirty-three T2D patients (18 men and 15 women; mean age, 59.3 ± 5.3 years) and 34 matched healthy control participants (17 men and 17 women; mean age, 60.1 ± 6.1 years) were recruited. Clinical characteristics of diabetic patients were assessed by considering a wide range of vascular and neurological parameters in order to exclude the presence of micro- and macro-vascular complications. Gender-specific muscle function was evaluated measuring the maximal voluntary isometric contraction (MVIC), and the endurance time at 50% of the MVIC at the shoulder and at the knee extensor muscles. RESULTS: Muscle strength in the upper body was similar among groups, whereas in the lower body, it was significantly reduced in T2D men (-16%) and women (-22%) compared with the controls. Additionally, the endurance time in both upper and lower body was significantly lower in T2D men (-18% and -29%) and women (-19% and -25%, respectively) than controls. CONCLUSIONS: Besides the reduction in strength, muscle dysfunction in T2D is characterized by a higher fatigability that affects both upper and lower body muscles. This effect is independent to the presence of diabetic complications and may represent a more sensitive marker of muscular dysfunction than muscle strength. Copyright © 2016 John Wiley & Sons, Ltd.

Differential control of respiratory frequency and tidal volume during high-intensity interval training.

NEW FINDINGS: What is the central question of this study? By manipulating recovery intensity and exercise duration during high-intensity interval training (HIIT), we tested the hypothesis that fast inputs contribute more than metabolic stimuli to respiratory frequency (fR ) regulation. What is the main finding and its importance? Respiratory frequency, but not tidal volume, responded rapidly and in proportion to changes in workload during HIIT, and was dissociated from some markers of metabolic stimuli in response to both experimental manipulations, suggesting that fast inputs contribute more than metabolic stimuli to fR regulation. Differentiating between fR and tidal volume may help to unravel the mechanisms underlying exercise hyperpnoea. Given that respiratory frequency (fR ) has been proposed as a good marker of physical effort, furthering the understanding of how fR is regulated during exercise is of great importance. We manipulated recovery intensity and exercise duration during high-intensity interval training (HIIT) to test the hypothesis that fast inputs (including central command) contribute more than metabolic stimuli to fR regulation. Seven male cyclists performed an incremental test, a 10 and a 20 min continuous time trial (TT) as preliminary tests. Subsequently, recovery intensity and exercise duration were manipulated during HIIT (30 s work and 30 s active recovery) by performing four 10 min and one 20 min trial (recovery intensities of 85, 70, 55 and 30% of the 10 min TT mean workload; and 85% of the 20 min TT mean workload). The work intensity of the HIIT sessions was self-paced by participants to achieve the best performance possible. When manipulating recovery intensity, fR , but not tidal volume (VT ), showed a fast response to the alternation of the work and recovery phases, proportional to the extent of workload variations. No association between fR and gas exchange responses was observed. When manipulating exercise duration, fR and rating of perceived exertion were dissociated from VT , carbon dioxide output and oxygen uptake responses. Overall, the rating of perceived exertion was strongly correlated with fR (r = 0.87; P < 0.001) but not with VT . These findings may reveal a differential control of fR and VT during HIIT, with fast inputs appearing to contribute more than metabolic stimuli to fR regulation. Differentiating between fR and VT may help to unravel the mechanisms underlying exercise hyperpnoea.

Exercise in type 2 diabetes: genetic, metabolic and neuromuscular adaptations. A review of the evidence.

The biological responses to exercise training are complex, as almost all organs and systems are involved in interactions that result in a plethora of adaptations at the genetic, metabolic and neuromuscular levels.To provide the general practitioner and the sports medicine professionals with a basic understanding of the genetic, metabolic and neuromuscular adaptations at a cellular level that occur with aerobic and resistance exercise in subjects with type 2 diabetes.For each of the three domains (genetic, metabolic and neuromuscular), the results of the major systematic reviews and original research published in relevant journals, indexed in PubMed, were selected. Owing to limitations of space, we focused primarily on the role of skeletal muscle, given its pivotal role in mediating adaptations at all levels.Generally, training-induced adaptations in skeletal muscle are seen as changes in contractile proteins, mitochondrial function, metabolic regulation, intracellular signalling, transcriptional responses and neuromuscular modifications. The main adaptation with clinical relevance would include an improved oxidative capacity derived from aerobic training, in addition to neuromuscular remodelling derived from resistance training. Both training modalities improve insulin sensitivity and reduce cardiovascular risk.Taken together, the modifications that occur at the genetic, metabolic and neuromuscular levels, work correlatively to optimise substrate delivery, mitochondrial respiratory capacity and contractile function during exercise.

Neuromuscular dysfunction in type 2 diabetes: underlying mechanisms and effect of resistance training.

Diabetic patients are at higher risk of developing physical disabilities than non-diabetic subjects. Physical disability appears to be related, at least in part, to muscle dysfunction. Several studies have reported reduced muscle strength and power under dynamic and static conditions in both the upper and lower limbs of patients with type 2 diabetes. Additional effects of diabetes include a reduction in muscle mass, quality, endurance and an alteration in muscle fibre composition, though the available data on these parameters are conflicting. The impact of diabetes on neuromuscular function has been related to the co-existence of long-term complications. Peripheral neuropathy has been shown to affect muscle by impairing motor nerve conduction. Also, vascular complications may contribute to the decline in muscle strength. However, muscle dysfunction occurs early in the course of diabetes and affects also the upper limbs, thus suggesting that it may develop independently of micro and macrovascular disease. A growing body of evidence indicates that hyperglycaemia may cause an alteration of the intrinsic properties of the muscle to generate force, via several mechanisms. Recently, resistance exercise has been shown to be an effective strategy to counteract the deterioration of muscular performance. High-intensity exercise seems to provide greater benefits than moderate-intensity training, whereas the effect of a power training is yet unknown. This article reviews the available literature on the impairment of muscle function induced by diabetes, the underlying mechanisms, and the effect of resistance training on this defect. Copyright © 2015 John Wiley & Sons, Ltd.

Exercise at lunchtime: effect on glycemic control and oxidative stress in middle-aged men with type 2 diabetes.

PURPOSE: Postprandial hyperglycemia and glycemic oscillations have been associated with increased oxidative stress. We sought to investigate the effect of two walking exercise protocols performed during lunchtime on glycemic control and oxidative stress in type 2 diabetic (T2D) patients. METHODS: Nine T2D patients participated in three randomized crossover trials; a control trial (Con), with participants having a standard lunch followed by their normal daily activities and two exercise trials (ContEx and Splitex). In ContEx, subjects performed 40 min of brisk walking 40 min after lunch, whereas in SplitEx the walking exercise was divided in two 20-min isoenergetic bouts, before and 40 min after meal. 24-h glycemic control was monitored by continuous glucose monitoring. 24-h urinary levels of 8-iso PGF2ɑ were measured as a marker of oxidative stress. RESULTS: SplitEx resulted in less time spent in moderate hyperglycemia after lunch vs ContEx (42.4 ± 38.7% vs 68.2 ± 32.7%, P = 0.04). ContEx reduced hyperglycemic time after breakfast consumed the morning after the exercise session (58.3 ± 29.6 Con vs 40.2 ± 33.4% ContEx, P = 0.02). Compared with Con, 24-h urinary isoprostanes were decreased both in ContEx (-68%, P = 0.02) and SplitEx (-63%, P = 0.04). CONCLUSIONS: Splitting an exercise session into two bouts, pre- and post-lunch, affects mainly the glycemic response to lunch, while a single-continuous isoenergetic session exerts its effect later in the 24-h period. Both exercise modalities effectively attenuate systemic oxidative stress with similar overall benefits.

Respiratory frequency is strongly associated with perceived exertion during time trials of different duration.

In order to provide further insight into the link between respiratory frequency (fR) and the rating of perceived exertion (RPE), the present study investigated the effect of exercise duration on perceptual and physiological responses during self-paced exercise. Nine well-trained competitive male cyclists (23 ± 3 years) performed a preliminary incremental ramp test and three randomised self-paced time trials (TTs) differing in exercise duration (10, 20 and 30 min). Both RPE and fR increased almost linearly over time, with a less-pronounced rate of increase when absolute exercise duration increased. However, when values were expressed against relative exercise duration, no between-trial differences were found in either RPE or fR. Conversely, between-trial differences were observed for minute ventilation (.VE), .VO2 and heart rate (HR), when values were expressed against relative exercise duration. Unlike the relationship between RPE and both .VE and HR, the relationship between RPE and fR was not affected by exercise duration. In conclusion, fR, but not .VE, HR or [.VO2, shows a strong relationship to RPE and a similar time course, irrespective of exercise duration. These findings indicate that fR is the best correlate of RPE during self-paced exercise, at least among the parameters and for the range of durations herein investigated.

Individual Optimal Frequency in Whole-Body Vibration: Effect of Protocol, Joint Angle, and Fatiguing Exercise.

Carlucci, F, Felici, F, Piccinini, A, Haxhi, J, and Sacchetti, M. Individual optimal frequency in whole-body vibration: effect of protocol, joint angle, and fatiguing exercise. J Strength Cond Res 30(12): 3503-3511, 2016-Recent studies have shown the importance of individualizing the vibration intervention to produce greater effects on the neuromuscular system in less time. The purpose of this study was to assess the individual optimal vibration frequency (OVF) corresponding to the highest muscle activation (RMSmax) during vibration at different frequencies, comparing different protocols. Twenty-nine university students underwent 3 continuous (C) and 2 random (R) different vibrating protocols, maintaining a squat position on a vibration platform. The C protocol lasted 50 seconds and involved the succession of ascending frequencies from 20 to 55 Hz, every 5 seconds. The same protocol was performed twice, having the knee angle at 120° (C) and 90° (C90), to assess the effect of joint angle and after a fatiguing squatting exercise (CF) to evaluate the influence of fatigue on OVF assessment. In the random protocols, vibration time was 20 seconds with a 2-minute (R2) and a 4-minute (R4) pauses between tested frequencies. Muscle activation and OVF values did not differ significantly in the C, R2, and R4 protocols. RMSmax was higher in C90 (p < 0.001) and in CF (p = 0.04) compared with the C protocol. Joint angle and fatiguing exercise had no effect on OVF. In conclusion, the shorter C protocol produced similar myoelectrical activity in the R2 and the R4 protocols, and therefore, it could be equally valid in identifying the OVF with considerable time efficiency. Knee joint angle and fatiguing exercise had an effect on surface electromyography response during vibration but did not affect OVF identification significantly.

Physical exercise as therapy for type 2 diabetes mellitus.

Many studies have highlighted the importance of physical activity (PA) for health, and recent evidence now points to the positive improvements associated with exercise in type 2 diabetes mellitus (T2DM). However, few physicians are willing to prescribe exercise as a therapy for diabetic patients. In addition, there is a lack of information on how to implement exercise therapy especially in long-term exercise regimens. The purpose of this manuscript is to summarize standards of exercise therapy for patients with T2DM, both in terms of prescribing and monitoring, according to the American College of Sports Medicine and the American Diabetes Association guidelines. We present details of the exercise therapies used in long-term studies, describing how the parameters for exercise prescription were applied in clinical practice. These parameters are described in terms of frequency, intensity, duration, mode and rate of progression in long-term therapeutic prescriptions. Individual responses to exercise dose are discussed, and critical issues to be considered in patients with underlying disease and in T2DM patients are highlighted.