Modeling the Power-Duration Relationship in Professional Cyclists During the Giro d'Italia

Vinetti, G, Pollastri, L, Lanfranconi, F, Bruseghini, P, Taboni, A, and Ferretti, G. Modeling the power-duration relationship in professional cyclists during the Giro d'Italia. J Strength Cond Res XX(X): 000-000, 2022-Multistage road bicycle races allow the assessment of maximal mean power output (MMP) over a wide spectrum of durations. By modeling the resulting power-duration relationship, the critical power (CP) and the curvature constant (W') can be calculated and, in the 3-parameter (3-p) model, also the maximal instantaneous power (P0). Our aim is to test the 3-p model for the first time in this context and to compare it with the 2-parameter (2-p) model. A team of 9 male professional cyclists participated in the 2014 Giro d'Italia with a crank-based power meter. The maximal mean power output between 10 seconds and 10 minutes were fitted with 3-p, whereas those between 1 and 10 minutes with the 2- model. The level of significance was set at p < 0.05. 3-p yielded CP 357 ± 29 W, W' 13.3 ± 4.2 kJ, and P0 1,330 ± 251 W with a SEE of 10 ± 5 W, 3.0 ± 1.7 kJ, and 507 ± 528 W, respectively. 2-p yielded a CP and W' slightly higher (+4 ± 2 W) and lower (-2.3 ± 1.1 kJ), respectively (p < 0.001 for both). Model predictions were within ±10 W of the 20-minute MMP of time-trial stages. In conclusion, during a single multistage racing event, the 3-p model accurately described the power-duration relationship over a wider MMP range without physiologically relevant differences in CP with respect to 2-p, potentially offering a noninvasive tool to evaluate competitive cyclists at the peak of training

High intensity interval training does not have compensatory effects on physical activity levels in older adults

Exercise has beneficial effects on older adults, but controversy surrounds the purported "compensatory effects" that training may have on total daily physical activity and energy expenditure in the elderly. We wanted to determine whether 8 weeks of high-intensity interval training (HIIT) induced such effects on physical activity and energy expenditure in healthy, active older adult men

Cardiorespiratory and Metabolic Responses to Sinusoidal Exercise of Moderate Intensity: Reliability of the Measurements and the Effects of Fatigue

The cardiorespiratory and metabolic responses to sinusoidal exercise, in which work rate follows an oscillating pattern, have been proposed to assess the effectiveness of the cardiorespiratory adjustments. The repetition of successive sinusoidal periods permits to simultaneously reduce the influence of random fluctuations and accentuate the underlying physiological response. Data analysis has been often performed by overlapping and averaging successive cycles assuming no differences among them, thus excluding the possible presence of fatigue throughout successive cycles. After assessing the reliability of the measurements during sinusoidal exercise, this study sought to investigate the possible differences among subsequent cycles of sinusoidal work. Eleven active volunteers (age: 28±6 yrs., body mass: 73±7 kg; stature: 1.79±0.06 m, maximum oxygen uptake (VO2max): 52 ml·kg−1·min−1) participated to the study that was conducted in accordance with the Basic Principles of the Declaration of Helsinki. After determining individual VO2max and critical power (CP) on a cycle ergometer, they underwent sinusoidal work rates characterized by an amplitude (A), a midpoint (MP) and a period equal to ±50W, 50W below CP and 240s, respectively, up to exhaustion. On a different day, participants repeated the same experimental session for reliability purposes. Expiratory ventilation (VE), oxygen uptake (VO2), carbon dioxide output (VCO2), and heart rate (fH) responses were fitted by the sinewave function that minimized the residuals. A, MP and the time-delay (tD, the latency between mechanical work rate and physiological responses) of all parameters were determined for each cycle. Reliability assessment between day 1 and 2 was expressed as Cronbach’s a and intraclass correlation coefficient (ICC). A one-way ANOVA for repeated measures tested the presence of differences among cycles. Regression analysis was also applied to explore possible relationship between each variables and time. Reliability analysis revealed a very high to high ICC values for most of the parameters, with the exception of A for VO2 and VCO2 and tD for fH (moderate reliability). A of VE and fH response increased and decreased with time, respectively (p<0.05). MP of VE and fH showed a positive regression that led to significantly higher values in the last compared to the first cycle; on the contrary, no changes were observed among cycles in all other MP data. tD was similar in each cycle for all the investigated parameters despite a very slight negative regression found for VCO2. In conclusion, most of the physiological responses to moderate sinusoidal exercise exhibited a high to very high reliability. Some of the cardiorespiratory parameters showed significant changes with time throughout the sinusoidal exercise possibly due to the onset of fatigue. Therefore, an approach that overlaps and averages all the cycles together should not be performed to avoid wrong estimation of physiological responses to sinusoidal exercise, unless the averaging approach involves only the first cycles

Aging: a portrait from gene expression profile in blood cells

The availability of reliable biomarkers of aging is important not only to monitor the effect of interventions and predict the timing of pathologies associated with aging but also to understand the mechanisms and devise appropriate countermeasures. Blood cells provide an easily available tissue and gene expression profiles from whole blood samples appear to mirror disease states and some aspects of the aging process itself. We report here a microarray analysis of whole blood samples from two cohorts of healthy adult and elderly subjects, aged 43 +/- 3 and 68 +/- 4 years, respectively, to monitor gene expression changes in the initial phase of the senescence process. A number of significant changes were found in the elderly compared to the adult group, including decreased levels of transcripts coding for components of the mitochondrial respiratory chain, which correlate with a parallel decline in the maximum rate of oxygen consumption (VO2max), as monitored in the same subjects. In addition, blood cells show age-related changes in the expression of several markers of immunosenescence, inflammation and oxidative stress. These findings support the notion that the immune system has a major role in tissue homeostasis and repair, which appears to be impaired since early stages of the aging process

Effects of eight weeks of aerobic interval training and of isoinertial resistance training on risk factors of cardiometabolic diseases and exercise capacity in healthy elderly subjects

We investigated the effect of 8 weeks of high intensity interval training (HIT) and isoinertial resistance training (IRT) on cardiovascular fitness, muscle mass-strength and risk factors of metabolic syndrome in 12 healthy older adults (68 yy \ub1 4). HIT consisted in 7 two-minute repetitions at 80%-90% of V\ucb\u99O2max, 3 times/w. After 4 months of recovery, subjects were treated with IRT, which included 4 sets of 7 maximal, bilateral knee extensions/flexions 3 times/w on a leg-press flywheel ergometer. HIT elicited significant: i) modifications of selected anthropometrical features; ii) improvements of cardiovascular fitness and; iii) decrease of systolic pressure. HIT and IRT induced hypertrophy of the quadriceps muscle, which, however, was paralleled by significant increases in strength only after IRT. Neither HIT nor IRT induced relevant changes in blood lipid profile, with the exception of a decrease of LDL and CHO after IRT. Physiological parameters related with aerobic fitness and selected body composition values predicting cardiovascular risk remained stable during detraining and, after IRT, they were complemented by substantial increase of muscle strength, leading to further improvements of quality of life of the subjects

Energetics of sinusoidal exercise below and across critical power and the effects of fatigue

Purpose: Previous studies investigating sinusoidal exercise were not devoted to an analysis of its energetics and of the effects of fatigue. We aimed to determine the contribution of aerobic and anaerobic lactic metabolism to the energy balance and investigate the fatigue effects on the cardiorespiratory and metabolic responses to sinusoidal protocols, across and below critical power (CP).Methods: Eight males (26.6 +/- 6.2 years; 75.6 +/- 8.7 kg; maximum oxygen uptake 52.8 +/- 7.9 mlmin(-1)kg(-1); CP 218 +/- 13 W) underwent exhausting sinusoidal cycloergometric exercises, with sinusoid midpoint (MP) at CP (CPex) and 50 W below CP (CP-50(ex)). Sinusoid amplitude (AMP) and period were 50 W and 4 min, respectively. MP, AMP, and time-delay (t(D)) between mechanical and metabolic signals of expiratory ventilation ([Formula: see text]), oxygen uptake ([Formula: see text]), and heart rate ([Formula: see text]) were assessed sinusoid-by-sinusoid. Blood lactate ([La-]) and rate of perceived exertion (RPE) were determined at each sinusoid.Results: [Formula: see text] AMP was 304 +/- 11 and 488 +/- 36 mlmin(-1) in CPex and CP-50(ex), respectively. Asymmetries between rising and declining sinusoid phases occurred in CPex (36.1 +/- 7.7 vs. 41.4 +/- 9.7 s for [Formula: see text] t(D up) and t(D down), respectively; P < 0.01), with unchanged t(D)s. [Formula: see text] MP and RPE increased progressively during CPex. [La-] increased by 2.1 mM in CPex but remained stable during CP-50(ex). Anaerobic contribution was larger in CPex than CP-50(ex).Conclusion: The lower aerobic component during CPex than CP-50(ex) associated with lactate accumulation explained lower [Formula: see text] AMP in CPex. The asymmetries in CPex suggest progressive decline of muscle phosphocreatine concentration, leading to fatigue, as witnessed by RPE

Metabolic and kinematic responses while walking and running on a motorised and a curved non-motorised treadmill

The purpose of this study was to assess metabolic and kinematic parameters (contact and flight time, step length and frequency) while walking at the preferred speed (1.44 ± 0.22 m · s−1) and while performing an incremental running test (up to exhaustion) on a motorised treadmill (MT) and on a curved non-motorised treadmill (CNMT). Twenty-five volunteers (24.1 ± 3.4 years; 64.7 ± 11.2 kg) participated in the study. Maximal running speed on MT was significantly larger (P < 0.001) than on CNMT (4.31 ± 0.50 vs. 3.75 ± 0.39 m · s−1) but no differences in heart rate or oxygen uptake were observed at this speed. The energy cost of walking (Cw) and running (Cr) were significantly greater (P < 0.001) on CNMT than on MT (37 and 17%, respectively). No major differences in kinematic parameters were observed at paired, submaximal, running speeds (2.22–3.89 m · s−1) but was systematically larger in CNMT (of about 340 ml · min−1 · kg−1). This systematic difference can be expressed in terms of a larger “equivalent speed” on CNMT (of about 0.42 m · s−1) and should be attributed to factors other than the kinematic ones, such as the belt characteristics (e.g. friction, type of surface and curvature)

Can a short-term hiking training speed up V'O2-on kinetic in healthy sedentary women?

We tested the hypothesis that two weeks of training performed at moderate intensity can induce a significant acceleration of the V'02-on kinetics in adultsedentary women. To this aim, breath-by-breath oxygen uptake (V'02) was measured in 8 women (25 yy \ub1 7; 68 kg \ub1 11,165 cm \ub1 8) during: i) an incrementai ramp cycling test up to exhaustion and; ii) during three consecutive square wave tests performed at approximately 50 % of V'02max before and immediately after atraining program of daiiy trekking (6-3 hour/d) performed at near sea level and on irregular and undulating terrain.Absolute and relative V'02max values did not increase as a result of the hiking training. The time Constant of the primary phase (t2: PRE: 23.1 s \ub1 8; POST 16.4 \ub1 6) of V02 kinetics were significantly smaller after training (P &lt; 0.05). Percent decrease of t2 was significantly and negative\uecy correlated with absolute V'O atbaseline (r = 0.69, P &lt; 0.05). It is concluded that two weeks of training performed at moderate intensity are able to induce a significant acceleration of the dynamicresponse of oxidative metabolism during exercise that is not paralleled by any increase of V'02max in healthy sedentary women. Moreover, the extent of the improvement is affected by the value of V'Omax at the baseline

Effect of Endurance and Strength Training on the Slow Component of O2 Kinetics in Elderly Humans

We compared the effects of 8 weeks of high intensity, aerobic interval training (HIT) and isoinertial resistance training (IRT) on: (i) O2 kinetics during heavy (HiEx) intensity exercise and; (ii) work economy during moderate (ModEx) intensity exercise in 12 healthy elderly men (69.3 ± 4.2 years). Breath-by-breath O2 and muscle deoxygenation ([HHb] by means of NIRS) were measured in HiEx and ModEx at identical workloads before and after trainings. In HiEx, O2 and HHb responses were modeled as tri-exponential and mono-exponential increasing functions, respectively. A two-way ANOVA for repeated measures analysis was made; Effect size (η2) was also evaluated. After HIT the amplitude and the time delay of the slow component of O2 uptake (O2sc) during HiEx were smaller (-32%; P = 0.045) and longer (+19.5%; P = 0.001), respectively. At Post IRT: (i) during ModEx, gain was lower (-5%; P = 0.050); (ii) during HiEx, τ2 (+14.4%; P = 0.050), d3 (+8.6%; P = 0.050), and τ3 (+17.2%; P = 0.050) were longer than at Pre IRT. After HIT, the decrease of the O2sc amplitude was likely induced by the beneficial effects of training on a more responsive O2 delivery and consumption cascade leading to a better muscle metabolic stability. IRT training was able to increase exercise economy during ModEx and to reduce the amplitude and delay the onset of O2sc during HiEx. These effects should be due to the reduction and the delayed recruitment of Type II muscle fibers. The better exercise economy and the delayed appearance of O2sc induced by IRT suggests that strength training might be included in endurance training programs to improve exercise economy and resistance to fatigue in this population of old subjects