Oxygen Uptake Slow Component and the Efficiency of Resistance Exercises

Methods to Assess Energy Expenditure of Resistance Exercise: A Systematic Scoping Review

BACKGROUND

Nutrition guidance for athletes must consider a range of variables to effectively support individuals in meeting energy and nutrient needs. Resistance exercise is a widely adopted training method in athlete preparation and rehabilitation and therefore is one such variable that will influence nutrition guidance. Given its prominence, the capacity to meaningfully quantify resistance exercise energy expenditure will assist practitioners and researchers in providing nutrition guidance. However, the significant contribution of anaerobic metabolism makes quantifying energy expenditure of resistance exercise challenging.

OBJECTIVE

The aim of this scoping review was to investigate the methods used to assess resistance exercise energy expenditure.

METHODS

A literature search of Medline, SPORTDiscus, CINAHL and Web of Science identified studies that included an assessment of resistance exercise energy expenditure. Quality appraisal of included studies was performed using the Rosendal Scale.

RESULTS

A total of 19,867 studies were identified, with 166 included after screening. Methods to assess energy expenditure included indirect calorimetry (n = 136), blood lactate analysis (n = 25), wearable monitors (n = 31) and metabolic equivalents (n = 4). Post-exercise energy expenditure was measured in 76 studies. The reported energy expenditure values varied widely between studies.

CONCLUSIONS

Indirect calorimetry is widely used to estimate energy expenditure. However, given its limitations in quantifying glycolytic contribution, indirect calorimetry during and immediately following exercise combined with measures of blood lactate are likely required to better quantify total energy expenditure. Due to the cumbersome equipment and technical expertise required, though, along with the physical restrictions the equipment places on participants performing particular resistance exercises, indirect calorimetry is likely impractical for use outside of the laboratory setting, where metabolic equivalents may be a more appropriate method.

Cardiorespiratory and aerobic demands of squat exercise

Squatting, a traditional resistance exercise classified as strength training, relies on anaerobic pathways, but its aerobic aspects remain unclear. We examined heart rate and oxygen demand during squats, exploring variations across different strength statuses. It fills gaps in understanding the cardiorespiratory effects of squatting, especially during multiple sets. Twenty-two young healthy resistance trained men (age: 28 ± 4 years) participated. Maximal oxygen consumption (V̇O2max) and 1 repetition maximum (RM) of squat were measured. Participants performed 5 sets of squat exercises at 65% of 1RM for 10 repetitions with 3-min rest intervals. Heart rate and pulmonary gas exchange were measured during the squat exercise. Participants were divided into high strength (HS; upper 50%) and low strength (LS; lower 50%) groups based on a median split of their 1 RM squat values (normalized to their body weight). During 5 sets of squat exercise, oxygen consumption (V̇O2) increased up to 47.8 ± 8.9 ml/kg/min, corresponding to 100.6% of predetermined V̇O2max. The HS group achieved a greater highest point of V̇O2 in relation to V̇O2max than the LS group (108.0 vs. 93.7%). During the exercise intervals, V̇O2 exceeded V̇CO2, while during the rest intervals, V̇CO2 surpassed V̇O2. Our findings suggest that the oxygen demand during squatting is notably substantial, which may vary according to the training status.

Impaired pulmonary and muscle function during moderate exercise in female patients recovered from SARS-CoV-2

This study aimed to assess pulmonary and muscle dysfunction by analyzing the slow component of oxygen uptake (VO2SC), and mechanical and ventilatory efficiency in adult women recovered from the severe acute respiratory syndrome coronavirus type II (SARS-CoV-2) during a constant load test. 32 women (N = 17 patients with SARS-CoV-2; N = 15 control group) performed two cardiopulmonary exercise tests (CPX) on a cycle ergometer. In the first test, the participants performed incremental CPX until extenuation. In the second test the participants performed a 10-min CPX at a constant load intensity (watts) corresponding to the first ventilatory threshold. There was a 48-72 h rest period between the two tests. There was a significant increase in the VO2SC in the patients recovered from SARS-CoV-2 (160.4 ± 60 mL min-1) in comparison with the healthy participants (59.6 ± 65 mL min-1) (P < 0.001). Mechanical efficiency significantly decreased in patients recovered from SARS-CoV-2 compared to the control group (P = 0.04). Ventilatory inefficiency significantly increased in the patients recovered from SARS-CoV-2 compared with the control group (P < 0.001). Adult women recovered from SARS-CoV-2 infection have important pulmonary and muscular dysfunction and fatigue which contributes to increasing the VO2SC and reducing mechanical and ventilatory efficiency during mild-moderate exercise at a constant load.

Similar Slow Component of Oxygen Uptake and Ventilatory Efficiency between an Aerobic Dance Session on an Air Dissipation Platform and a Constant-Load Treadmill Test in Healthy Women

There is a lack of evidence about the slow component of oxygen consumption (V.O2sc) and ventilatory efficiency (slope VE·VCO2−1) during an aerobic dance (AD) session on an air dissipation platform (ADP) despite the key role played in endurance exercises. This research was designed to assess V.O2sc, ventilatory efficiency, and blood lactate concentration by comparing two exercise modes: AD session on an ADP versus treadmill test at a constant-load intensity of the first ventilatory threshold (VT1). In the first session, an incremental treadmill test was completed. In sessions 2 and 3, the participants were randomly assigned to the AD session on an ADP or to a treadmill constant-load test at VT1 intensity to determine their cardioventilatory responses. In addition, their blood lactate levels and ratings of perceived exertion (RPE, CR-10) were evaluated. No significant differences were found between the constant-load treadmill test and AD session on an ADP with respect to V.O2sc, VE VCO2−1 slope, and RPE (p > 0.05). Higher blood lactate concentrations were observed in an AD session on an ADP than in a constant-load treadmill test at 10 min (p = 0.003) and 20 min (p < 0.001). The two different exercise modalities showed similar V.O2sc and VE·VCO2−1 slope, even though the blood lactate concentrations were different.

Circulating nitrate-nitrite reduces oxygen uptake for improving resistance exercise performance after rest time in well-trained CrossFit athletes

This study aimed to determine the effects of circulating nitrate plus nitrite (NOx) concentrations on resistance exercise performance, VO₂ and biomarkers of muscle damage. Eleven well-trained male CrossFit athletes (29.2 ± 3.7 years, 78.9 ± 5.4 kg, 175.1 ± 6.3 cm) carried out a resistance exercise test after drinking 140 mL of beetroot juice (BJ) or placebo. The test consisted of repeating the same resistance exercise routine twice: wall ball shots plus full back squat with 3-min rest (1st routine) or without rest (2nd routine) between the two exercises. Higher NO_x plasma levels were verified after BJ than placebo in the pretest and post-test (p < 0.001). A higher number of repetitions was observed after BJ intake compared to placebo in the full back squat exercise during the first routine (p = 0.004). A significantly reduced VO₂ was detected after BJ intake compared to placebo during rest and full back squat execution in the first routine (p < 0.05). Plasma myoglobin concentrations were significantly increased with BJ compared to placebo (p = 0.036). These results showed that plasma NOx levels reduced VO₂ after BJ intake during rest time. These reduced VO₂ was a key factor for improving full back squat performance during the first routine.

Multimodal Benefits of Exercise in Patients With Multiple Sclerosis and COVID-19

Multiple sclerosis (MS) is a demyelinating disease characterized by plaque formation and neuroinflammation. The plaques can present in various locations, causing a variety of clinical symptoms in patients with MS. Coronavirus disease-2019 (COVID-19) is also associated with systemic inflammation and a cytokine storm which can cause plaque formation in several areas of the brain. These concurring events could exacerbate the disease burden of MS. We review the neuro-invasive properties of SARS-CoV-2 and the possible pathways for the entry of the virus into the central nervous system (CNS). Complications due to this viral infection are similar to those occurring in patients with MS. Conditions related to MS which make patients more susceptible to viral infection include inflammatory status, blood-brain barrier (BBB) permeability, function of CNS cells, and plaque formation. There are also psychoneurological and mood disorders associated with both MS and COVID-19 infections. Finally, we discuss the effects of exercise on peripheral and central inflammation, BBB integrity, glia and neural cells, and remyelination. We conclude that moderate exercise training prior or after infection with SARS-CoV-2 can produce health benefits in patients with MS patients, including reduced mortality and improved physical and mental health of patients with MS.

The Relationship between Resistance Exercise Performance and Ventilatory Efficiency after Beetroot Juice Intake in Well-Trained Athletes

The assessment of ventilatory efficiency is critical to understanding the matching of ventilation (VE) and perfusion in the lungs during exercise. This study aimed to establish a causal physiological relationship between ventilatory efficiency and resistance exercise performance after beetroot juice (BJ) intake. Eleven well-trained males performed a resistance exercise test after drinking 140 mL of BJ (~12.8 mmol NO3-) or a placebo (PL). Ventilatory efficiency was assessed by the VE•VCO2-1 slope, the oxygen uptake efficiency slope and the partial pressure of end-tidal carbon dioxide (PetCO2). The two experimental conditions were controlled using a randomized, double-blind crossover design. The resistance exercise test involved repeating the same routine twice, which consisted of wall ball shots plus a full squat (FS) with a 3 min rest or without a rest between the two exercises. A higher weight lifted was detected in the FS exercise after BJ intake compared with the PL during the first routine (p = 0.004). BJ improved the VE•VCO2-1 slope and the PetCO2 during the FS exercise in the first routine and at rest (p < 0.05). BJ intake improved the VE•VCO2-1 slope and the PetCO2 coinciding with the resistance exercise performance. The ergogenic effect of BJ could be induced under aerobic conditions at rest.

Practical Recommendations Relevant to the Use of Resistance Training for COVID-19 Survivors

The novel coronavirus disease (COVID-19) has emerged at the end of 2019 and caused a global pandemic. The disease predominantly affects the respiratory system; however, there is evidence that it is a multisystem disease that also impacts the cardiovascular system. Although the long-term consequences of COVID-19 are not well-known, evidence from similar diseases alerts for the possibility of long-term impaired physical function and reduced quality of life, especially in those requiring critical care. Therefore, rehabilitation strategies are needed to improve outcomes in COVID-19 survivors. Among the possible strategies, resistance training (RT) might be particularly interesting, since it has been shown to increase functional capacity both in acute and chronic respiratory conditions and in cardiac patients. The present article aims to propose evidence-based and practical suggestions for RT prescription for people who have been diagnosed with COVID-19 with a special focus on immune, respiratory, and cardiovascular systems. Based on the current literature, we present RT as a possible safe and feasible activity that can be time-efficient and easy to be implemented in different settings.

Understanding the effects of beetroot juice intake on CrossFit performance by assessing hormonal, metabolic and mechanical response: a randomized, double-blind, crossover design

BACKGROUND

Acute beetroot juice (BJ) intake has shown to enhance aerobic and anaerobic performance. However, no studies have evaluated the effects of BJ intake on CrossFit (CF) performance by linking hormonal, metabolic, and mechanical responses. The purpose of this study was to determine the causal physiological association between hormonal, metabolic and mechanical responses, and CF workouts performance after acute BJ intake.

METHODS

Twelve well-trained male practitioners undertook a CF workout after drinking 140 mL of BJ (~ 12.8 mmol NO3-) or placebo. The two experimental conditions (BJ or placebo) were administered using a randomized, double-blind, crossover design. The CF workout consisted of repeating the same exercise routine twice: Wall ball (WB) shots plus full back squat (FBS) with 3-min rest (1st routine) or without rest (2nd routine) between the two exercises. A 3-min rest was established between the two exercise routines.

RESULTS

An interaction effect was observed in the number of repetitions performed (p = 0.04). The Bonferroni test determined a higher number of repetitions after BJ than placebo intake when a 3-min rest between WB and FBS (1st routine) was established (p = 0.007). An interaction effect was detected in cortisol response (p = 0.04). Cortisol showed a higher increase after BJ compared to placebo intake (76% vs. 36%, respectively). No interaction effect was observed in the testosterone and testosterone/cortisol ratio (p > 0.05). A significant interaction effect was found in oxygen saturation (p = 0.01). A greater oxygen saturation drop was observed in BJ compared to placebo (p <  0.05). An interaction effect was verified in muscular fatigue (p = 0.03) with a higher muscular fatigue being observed with BJ than placebo (p = 0.02).

CONCLUSIONS

BJ intake improved anaerobic performance only after the recovery time between exercises. This increase in performance in the first routine probably generated greater hypoxia in the muscle mass involved, possibly conditioning post-exercise performance. This was observed with a fall in oxygen saturation and in muscle fatigue measured at the end of the CF workout. The greatest perceived changes in cortisol levels after BJ intake could be attributed to the nitrate-nitrite-nitric oxide pathway.

Resistance Training Safety during and after the SARS-Cov-2 Outbreak: Practical Recommendations

In December of 2019, there was an outbreak of a severe acute respiratory syndrome caused by the coronavirus 2 (SARS-CoV-2 or COVID-19) in China. The virus rapidly spread into the whole world causing an unprecedented pandemic and forcing governments to impose a global quarantine, entering an extreme unknown situation. The organizational consequences of quarantine/isolation are absence of organized training and competition, lack of communication among athletes and coaches, inability to move freely, lack of adequate sunlight exposure, and inappropriate training conditions. The reduction of mobility imposed to contain the advance of the SARS-Cov-2 pandemic can negatively affect the physical condition and health of individuals leading to muscle atrophy, progressive loss of muscle strength, and reductions in neuromuscular and mechanical capacities. Resistance training (RT) might be an effective tool to counteract these adverse consequences. RT is considered an essential part of an exercise program due to its numerous health and athletic benefits. However, in the face of the SARS-Cov-2 outbreak, many people might be concerned with safety issues regarding its practice, especially in indoor exercise facilities, such as gyms and fitness centers. These concerns might be associated with RT impact in the immune system, respiratory changes, and contamination due to equipment sharing and agglomeration. In this current opinion article, we provide insights to address these issues to facilitate the return of RT practices under the new logistical and health challenges. We understand that RT can be adapted to allow its performance with measures adopted to control coronavirus outbreak such that the benefits would largely overcome the potential risks. The article provides some practical information to help on its implementation.

Ventilatory efficiency during constant-load test at lactate threshold intensity: Endurance versus resistance exercises

There is a lack of evidence about the ventilatory efficiency in resistance exercises despite the key role played in endurance exercises. This study aimed to compare the cardiorespiratory, metabolic responses and ventilatory efficiency between half-squat (HS) and cycle ergometer exercises during a constant-load test at the lactate threshold (LT) intensity. Eighteen healthy male participants were randomly assigned in a crossover design to carry out HS or cycle ergometer tests. For the three HS tests, a one repetition maximum (1RM) test was performed first to determine the load (kg) corresponding to the 1RM percentages. In the second test, the incremental HS exercise was carried out to establish the load (kg) at the LT intensity. Finally, a constant-load HS test was performed at the LT intensity. The first cycle ergometer test was incremental loading to determine the intensity in watts corresponding to the LT, followed by a constant-load test at the LT intensity. A recovery time of 48 hours between each test was established. During both constant-load test, cardiorespiratory and metabolic responses were monitored. A significant exercise mode x time interaction effect was only detected in oxygen uptake (VO2), heart rate, and blood lactate (p < 0.001). No differences were found between the two types of exercise in ventilatory efficiency (p >0.05). Ventilation (VE) and carbon dioxide were highly correlated (p <0.001) in the cycle ergometer (r = 0.892) and HS (r = 0.915) exercises. In the VO2 efficiency slope (OUES), similarly significant and high correlations (p <0.001) were found between VO2 and log10 VE in the cycle ergometer (r = 0.875) and in the HS (r = 0.853) exercise. Although the cardioventilatory responses were greater in the cycle ergometer test as compared to HS exercise, ventilatory efficiency was very similar between the two exercise modalities in a predominantly aerobic metabolism.

The Slow Component of Oxygen Uptake and Efficiency in Resistance Exercises: A Comparison With Endurance Exercises

Introduction

There is a lack of information regarding the slow component of oxygen uptake (VO₂sc) and efficiency/economy in resistance exercises despite the crucial role played in endurance performance.

Purpose

this study aimed to compare the VO₂sc, efficiency/economy, metabolic, cardiorespiratory responses, rating of perceived effort and mechanical fatigue between cycling and half-squat (HS) exercises during a constant-load test at lactate threshold (LT₁) intensity.

Methods

Twenty-one healthy men were randomly assigned in a crossover design to perform cycle-ergometer or HS tests. The order of the two cycle ergometer tests was an incremental test for determining load-intensity in watts (W) at LT₁, followed by a constant-load test at the LT₁ intensity. For the three HS tests, the order was a 1RM test to determine the load (kg) corresponding to the 1RM percentages to be used during the second test, incremental HS exercise to establish the load (kg) at the LT₁ intensity, and finally, a constant-load HS test at the LT₁ intensity. A rest period of 48 h between each test was established. During the HS and cycle-ergometer constant-load tests, cardiorespiratory and metabolic responses were recorded. Lower limbs fatigue was determined by a jump test before and after the constant-load tests.

Results

A significant exercise mode × time interaction effect was detected in VO₂, heart rate, energy expenditure (EE), gross efficiency (GE), and economy (p < 0.05). A significant and sustained VO₂ raise was confirmed in HS exercise (p < 0.05) and a steady-state VO₂ was revealed in cycle-ergometer. A higher GE and economy were obtained in HS test than in cycle-ergometer exercise (p < 0.001). In both exercises, a non-significant decrease was observed in GE and economy (p > 0.05). Lower limbs fatigue was only detected after constant-load HS test.

Conclusion

Although the VO₂, heart rate and EE responses were higher in cycling exercise, the constant-load HS test induced a greater VO₂sc and EE raise than the cycling test in a predominantly aerobic metabolism. These results could explain a decrease observed in jump performance only after HS test. GE and economy could benefit from the eccentric phase of the HS exercise.