Supplementation of caffeine and sodium bicarbonate together could not improve performance and performance-related factors in CrossFit participants: a randomized, double-blind, placebo-controlled study

BACKGROUND

CrossFit includes weightlifting, powerlifting, and gymnastics in various combinations of overloads and repetitions with limited rest periods or no rest between training sets. Due to the novelty of CrossFit, there are few studies on the effect of nutritional strategies on the acute response to this type of sports activity. This study examined the effect of caffeine (CAF) and sodium bicarbonate (NaHCO₃) ingestion separately and in combination on the performance and rate of perceived exertion (RPE) during the Cindy CrossFit workout (Cindy) in CrossFit participants.

METHOD

In a double-blind, crossover, randomized, placebo-controlled trial, 20 CrossFit participants underwent five experimental conditions, including control (CON), placebo (PLA), CAF, NaHCO₃, and CAF + NaHCO₃ (7 days to wash-out between assessment sessions) before completing the Cindy protocol (age: 22.30 ± 2.88 years, body mass index: 25.22 ± 2.51 kg/m²). Capsules containing 6 mg/kg body weight (BW) CAF were consumed 50 min before the Cindy workout while 0.3 g/kg BW NaHCO₃ was consumed for 3 days, leading to 120, 90, and 60 min before the Cindy workout. Performance, RPE, muscular power (MP), handgrip strength (HGS), and maximum heart rate (MHR) were measured before and shortly after the Cindy.

RESULTS

The performance of CrossFit participants during the Cindy protocol was not significantly improved following CAF, NaHCO₃, and CAF + NaHCO₃ (P > 0.05). In contrast, RPE during and at the end of the Cindy was significantly decreased following CAF + NaHCO₃ consumption compared to PLA and CON (P = 0.001, P = 0.02). However, MP (P = 0.82) and HGS (P = 0.52) were not significantly different between conditions. Also, MHR was significantly greater following CAF, NaHCO₃, and CAF + NaHCO₃ consumption than CON (P = 0.01).

CONCLUSION

CAF + NaHCO₃ supplementation decreased RPE despite significantly increased MHR, but with no significant effect on performance, HGS, or MP. Therefore, CrossFit participants may benefit from the ergogenic effects of CAF and NaHCO₃ when consumed separately or together.

The Effects of a 10-Week Aerobic and Unilateral Lower Extremity Resistance Training Program on Amplitude and Nerve Conduction Velocity of Sensory and Motor Nerves in Diabetic Patients with Neuropathy

This study aimed to investigate the effects of 10-week aerobic and unilateral lower extremity resistance training on nerve conduction velocity and amplitude of sensory and motor nerves in diabetic patients with neuropathy. This clinical trial was conducted on twenty women and men (aged 30-60 years old) with diabetic neuropathy. Participants were randomly assigned to one of the two groups: an exercise group (EG; n = 10) and a control group (CG; n = 10). The EG performed a 10-week programme with one session of aerobic exercises (40% to 70% of HR reserve), supplemented with one session of specific lower extremity resistance exercises (60-90 min/day) on the same day for four days per week. The CG subjects performed their regular daily activities. The nerve conduction velocity, amplitude of sensory and motor nerves and glycosylated haemoglobin A1c were measured before and after the intervention. The repeated-measures ANOVA showed a significant increase in the conduction velocity of the sural sensory nerve as well as the peroneal motor nerve (p < 0.01, p < 0.01). The changes in the conduction velocity of the tibial nerve were similar when compared to the control group (p > 0.05). A significantly greater decrease in glycosylated haemoglobin was also observed in the EG group (p < 0.01). Performing 10 weeks of aerobic and specific unilateral lower extremity exercises can improve the function of sensory and motor nerves and improve symptoms in diabetic patients with neuropathy. Given the limited studies in this area, the exact mechanisms of this performance improvement need further examination.

Swimming exercise reduces oxidative stress and liver damage indices of male rats exposed to electromagnetic radiation

OBJECTIVES

Hepatic damage caused by oxidative stress is one of the problems associated with the emission of electromagnetic radiation (EMR). In this study, the effects of swimming exercise (SE) on oxidative stress and liver cell damage caused by EMR emission in rats were investigated.

METHODS

Thirty-two rats (8 weeks old) were randomly divided into four groups, including control (C), EMR, SE, and EMR + SE. During four weeks, the animals engaged in SE (30 min/session, 5session/week) and were also exposed to EMR (4 h/day, seven days/week) emission from a Wi-Fi _2.45GHZ router. The liver and blood samples were collected at 48 h after completing four weeks of SE to assess histopathological damage, oxidative stress, and liver enzymes.

KEY FINDINGS

Tissue sections showed severe liver damage in the EMR group compared to the C group, while the SE attenuated the liver damage. In the EMR group, compared to the C, SE and EMR + SE groups, the activity of superoxide dismutase (SOD) and catalase (CAT) decreased significantly, and the concentration of malondialdehyde (MDA) and liver enzymes (AST, ALT, and ALP) increased significantly (P < 0.05). Swimming exercise in the SE and EMR + SE groups compared to EMR led to a significant increase in the activity of SOD and CAT and a significant decrease in the concentration of MDA and liver enzymes (P < 0.05).

CONCLUSION

The study findings showed that the SE is beneficial in attenuating the harmful effects of RF-EMR emitted from the Wi-Fi on the liver.

Lack of Evidence for Crossover Fatigue with Plantar Flexor Muscles

The occurrence and mechanisms underlying non-local or crossover muscle fatigue is an ongoing issue. This study aimed to investigate crossover fatigue of the plantar flexor muscles. Sixteen recreationally active males (n = 6) and females (n = 10) visited the laboratory for four sessions and performed a single 5-s pre-test maximal voluntary isometric contraction (MVIC) with each plantar flexors muscle. Thereafter, the fatigue intervention involved two 100-s MVICs (60-s recovery) with their dominant plantar flexors or rested for 260-s (control). Subsequently, in two separate sessions, Hoffman reflexes (H-reflex) were evoked in the non-dominant, non-exercised, leg before and following the dominant leg fatigue or control intervention (Fatigue-Reflex and Control-Reflex conditions). MVIC forces and volitional (V)-waves were monitored in the non-dominant leg in the other two sessions (Fatigue-MVIC and Control-MVIC) before and after the intervention (fatigue or control) as well as during 12 repeated MVICs and immediately thereafter. Despite the force reduction in the dominant leg (42.4%, p = 0.002), no crossover force deficit with single (F_(1,9) = 0.02, p = 0.88, pƞ² = 0.003) or repeated (F_(1,9) = 0.006, p = 0.93, pƞ² = 0.001) MVIC testing were observed. The H-reflex did not change after the fatigue (F_(1,7) = 0.51; p = 0.49; pƞ² = 0.06) or repeated MVICs (F_(1,8) = 0.27; p = 0.61; pƞ² = 0.03). There were also no crossover effects of fatigue on the V-wave with single (F_(1,8) = 3.71, p = 0.09, pƞ² = 0.31) or repeated MVICs (F_(1,6) = 1.45, p = 0.27, pƞ² = 0.19). Crossover fatigue was not evident with the plantar flexors nor any significant changes in H-reflex and V-waves in the soleus muscle. This finding suggests that crossover fatigue may not necessarily occur in slow-twitch predominant muscle groups.

Effect of eccentric and concentric contraction mode on myogenic regulatory factors expression in human vastus lateralis muscle

Skeletal muscle contractions are caused to release myokines by muscle fiber. This study investigated the myogenic regulatory factors, as MHC I, IIA, IIX, Myo-D, MRF4, Murf, Atrogin-1, Decorin, Myonection, and IL-15 mRNA expression in the response of eccentric vs concentric contraction. Eighteen healthy men were randomly divided into two eccentric and concentric groups, each of 9 persons. Isokinetic contraction protocols included maximal single-leg eccentric or concentric knee extension tasks at 60°/s with the dominant leg. Contractions consisted of a maximum of 12 sets of 10 reps, and the rest time between each set was 30 s. The baseline biopsy was performed 4 weeks before the study, and post-test biopsies were taken immediately after exercise protocols from the vastus lateralis muscle. The gene expression levels were evaluated using Real-Time PCR methods. The eccentric group showed a significantly lower RPE score than the concentric group (P ≤ 0.05). A significant difference in MyoD, MRF4, Myonection, and Decorin mRNA, were observed following eccentric or concentric contractions (P ≤ 0.05). The MHC I, MHC IIA, IL-15 mRNA has been changed significantly compared to the pre-exercise in the concentric group (P ≤ 0.05). While only MHC IIX and Atrogin-1 mRNA changed significantly in the eccentric group (P ≤ 0.05). Additionally, the results showed a significant difference in MyoD, MRF4, IL-15, and Decorin at the follow-up values between eccentric or concentric groups (P ≤ 0.05). Our findings highlight the growing importance of elucidating the different responses of muscle growth factors associated with a myogenic activity such as MHC IIA, Decorin, IL-15, Myonectin, Decorin, MuRF1, and MHC IIX mRNA in following various types of exercise.

Comparing the Effects of Rosemary Extract and Treadmill Exercise on the Hippocampal Function and Antioxidant Capacity in Old Rats

Introduction:

A sequence of time-dependent changes can affect the brain’s functional capacity.

This study aimed at investigating the effects of Forced Aerobic Exercise (FAE) versus the Rosemary Extract (RE) on the learning abilities and oxidative stress modulation in rats.

Methods:

Young and old rats received daily FAE and RE for 3 months. Using the Passive Avoidance (PA) test, we evaluated the learning and memory of the rats by Step-Through Latency (STL) score. We measured the Superoxide Dismutase (SOD), Glutathione Peroxidase (GPx), Catalase (CATA), Malondialdehyde (MDA) enzymes levels, and Total Antioxidant Capacity (TAC) in the hippocampus

Results:

FAE could significantly increase the STL score (P<0.001) among old rats similar to the rosemary extract consumption. The SOD, GPx, and CATA enzyme activities and the level of TAC significantly increased by the treatments (exercise: P<0.001 for SOD and TAC and P<0.05 for CATA, exercise/rosemary: P<0.001 for all enzymes, and rosemary: P<0.01 for SOD and TAC). Furthermore, the MDA level significantly decreased by the treatments (exercise and exercise/rosemary: P<0.001, rosemary: P<0.01). The partial Pearson test revealed the significant positive correlations between the score of STL (day 2) with the SOD (P<0.01) and TAC (P<0.05) levels and negative correlations between the MDA level and STL score in both days (P<0.05 for the first day and P<0.001 for the second day).

Conclusion:

Similar to the rosemary extract, FAE could increase the working memory and antioxidants activity in old rats in 3 months.

The Combined Effects of 6 Weeks of Jump Rope Interval Exercise and Dark Chocolate Consumption on Antioxidant Markers in Obese Adolescent Boys

Research has shown that both dark chocolate and exercise training may have favorable effects on antioxidant function in obese cohorts. However, their combined effect has not been established. We assessed the influences of six weeks of dark chocolate consumption combined with jump rope exercise on antioxidant markers in adolescent boys with obesity. Fifty adolescent boys with obesity (age = 15 ± 1 years) were randomly assigned into one of four groups; jump rope exercise + white chocolate consumption (JW; n = 13), jump rope exercise + dark chocolate consumption (JD; n = 13), dark chocolate consumption (DC; n = 12), or control (C; n = 12). Two participants dropped out of the study. Participants in JW and JD groups performed jump rope exercise three times per week for six weeks. Participants in the DC and JD groups consumed 30 g of dark chocolate containing 83% of cocoa during the same period. Serum concentrations of superoxide dismutase (SOD), total antioxidant capacity (TAC), glutathione peroxidase (GPx), and thiobarbituric acid reactive substances (TBARS) were evaluated prior to and after the interventions. All 3 intervention groups noted significant (p < 0.01) increases in serum concentrations of TAC, SOD, and GPx from baseline to post-test. In contrast, all intervention groups showed significantly reduced serum concentrations of TBARS from pre- to post-test (p ≤ 0.01). Bonferroni post hoc analysis revealed that post-test serum concentrations of TAC in the JD group were significantly greater than C (p < 0.001), DC (p = 0.010), and JW (p < 0.001) groups. In addition, post-test serum concentrations of SOD in the JD group were significantly greater than C group (p = 0.001). Post-test serum concentrations of GPx in the JD group were significantly greater than C (p < 0.001), DC (p = 0.021), and JW (p = 0.032) groups. The post-test serum concentrations of TBARS in the JD group was significantly lower than C (p < 0.001). No other significant between-group differences were observed. The current study provides evidence that dark chocolate consumption in combination with jump rope exercise is more efficient in improving antioxidant capacity than dark chocolate consumption or jump rope exercise alone among obese adolescent boys.

Inflammatory, antioxidant and glycemic status to different mode of high-intensity training in type 2 diabetes mellitus

BACKGROUND

Exercise has traditionally been used and prescribed as an effective and suitable way to treat type 2 diabetics Mellitus (T2DM). In this regard, we compared inflammatory, antioxidant, and glycemic status to different kinds of high-intensity interval training (strength training, HIIT, and HIIT + ST) in patients with T2DM.

METHODS AND RESULTS

Fifty-nine T2DM patients (age = 45-60 yrs) were randomly divided to strength training (ST) (n = 15), high intensity interval training (HIIT) (n = 16), HIIT + ST (n = 15) or served as control (CON) (n = 13) groups. Experimental groups performed three training sessions/week for 12 weeks. Inflammatory, antioxidant, glycemic factors, and anthropometric parameters were evaluated at baseline and after the 12 weeks of interventions. Training HIIT groups significantly improved antioxidant factors, lipid profile, and glycemic parameters (P ≤ 0.05). Interleukin 6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-α (TNF-α) significantly decreased in the three training groups. As a result of training, the overall inflammatory and antioxidant status were improved considerably in all three training groups compared to the CON group (P ≤ 0.05). In addition, there were significant differences in CRP at the follow-up values between ST and CON groups (P ≤ 0.05). Exercise time and TC were significantly improved in HIIT than in the CON group (P ≤ 0.05). The results showed a significant difference between the HIIT + ST group and the CON group in VO2_peak (P ≤ 0.05).

CONCLUSIONS

Our results showed improvement in inflammatory factors, antioxidants, and glycemic parameters in all training groups regardless of their type. However, for more benefits in T2DM patients, combination exercises can be suggested.

Saffron (Crocus sativus L.) in combination with resistance training reduced blood pressure in the elderly hypertensive men: A randomized controlled trial

AIMS

We aimed to determine the independent and combined effects of saffron and resistance training on blood pressure (BP) and some chemical biomarkers in the elderly with hypertension.

METHODS

The present study was a randomized clinical trial on hypertensive men aged 60-70 years who were assigned to a control group (CO) and 3 experimental groups; resistance training (RT); saffron (S); and resistance training + saffron (RTS) for 12 weeks. Dynamic resistance training was applied with moderate intensity. Patients in S and RTS received 1 tablet containing 200 mg of saffron daily. BP variables, chemical biomarkers and anthropometric indicators were measured at weeks 0, 6, 12 and 18. Data were analysed by repeated measurements ANOVA with 95% confidence interval (CI).

RESULTS

In comparison to the CO (153.3 ± 1.18, CI = 10.9-20.2, P < .001) and S (143.3 ± 1.18, CI = 0.97-10.2, P = .01), RTS (137.7 ± 1.18) reduced systolic BP with the effect size partial η² of 0.68. Nitric oxide increased in the RTS compared to the CO group (CI = 0.13-0.62, P = .001). There was a significant increase and decrease in adiponectin and endothelin-1 in the S (CI = 0.03-1.20, P = .012; CI = 4.30-17.3, P < .001) and RT (CI = 0.36-1.60, P < .001; CI = 2.26-15.3, P = .003) compared to the CO, respectively. The partial η² for nitric oxide, adiponectin and ET-1 were 0.35, 0.35 and 0.38, respectively. There was no significant difference between the groups for atrial natriuretic peptide.

CONCLUSIONS

Resistance training and consumption of saffron can improve BP in the elderly with hypertension by affecting the factors involved in altering vascular endothelial resistance. The present study was approved by the Ethics Committee of Iran's sports science research institution (IR.SSRC.REC.1398.020) and registered at the Iranian Registry of Clinical Trials (IRCT20190731044398N1).

Voluntary wheel running promotes improvements in biomarkers associated with neurogenic activity in adult male rats

In rodents, hippocampal neurogenesis and synaptogenesis phenomena are affected by exercise. However, the role of exercise parameters such as intensity, duration, and mode on molecular mechanisms involved in these processes has not been elucidated. In this study, we evaluated the effects of different intensities and modes of running on the expression of genes contributing to neuronal differentiation and synapse formation in the hippocampus of adult male rats. Adult male Wistar rats (n = 24) were randomly divided into control, low-intensity running (LIR), high-intensity running (HIR), and the voluntary wheel running (WR) conditions. Changes in the expression of microRNA-124 (miR-124), microRNA-132 (miR-132), and their respective targets, were analyzed using quantitative RT-PCR and Western blotting techniques. Our results showed that WR compared to treadmill running increased miR-124 and miR-132 expression, while reducing the expression of their respective targets, glucocorticoid receptor (GR), SRY-Box 9 (SOX9), and GTP-activated protein P250 (P250GAP). Differences in expression levels were statistically significant (ps < 0.05), except for the expression of GR in HIR (P = 0.09). Moreover, the expression level of gene coding for the transcription factor cAMP-response element binding protein (CREB) was significantly higher in the WR group compared to the treadmill running groups (P = 0.001). Western blotting techniques indicated that the level of the CREB protein was higher in WR compared to the other groups qualitatively. These findings demonstrated a more dramatic effect for voluntary running on biomarkers that are associated with stimulating neurogenesis and synapse formation in the hippocampus of male rats compared with forced treadmill running. In addition, greater positive effects were observed for lower-intensity treadmill running as compared with high-intensity running.

Voluntary wheel running stimulates the expression of Nrf-2 and interleukin-10 but suppresses interleukin-17 in experimental autoimmune encephalomyelitis

Multiple sclerosis is an inflammatory and neurodegenerative disease of the central nervous system in which the immune cells attack the myelin sheath of the nerves, leading to axonal damage, inflammation, immune cell infiltration, and demyelination of the brain and spinal cord. These detrimental changes cause some impairments, such as depression, motor deficit, and cognitive dysfunction, affecting the quality of life in MS patients and their social activities. The present study assessed the impact of 6-week voluntary exercise prior to disease onset on the expression of Nrf-2, IL-10, IL-17, as well as the degree of lymphocyte infiltration in the spinal cord and disease severity in the chronic period of the EAE (30 days post-induction). The results showed that voluntary wheel running stimulated the expression of Nrf-2 and IL-10, while decreased the expression of IL-17, the rate of lymphocyte infiltration, and the severity of EAE at the chronic period of the disease. Thus, alterations in lifestyle, such as regular exercise, may modulate inflammation and disease severity in patients with MS.

High-intensity interval training-induced hypertrophy in gastrocnemius muscle via improved IGF-I/Akt/FoxO and myostatin/Smad signaling pathways in rats

Objective

It has been shown that high-intensity interval training (HIIT) leads to skeletal muscle hypertrophy; however, its mechanisms of cellular and molecular regulation are still unclear. The purpose of this study was to investigate the effect of HIIT on muscle hypertrophy and major signal transduction pathways.

Design

12 male rats were randomly divided into two groups: control and HIIT. The exercise group performed 30-min HIIT in each session (5 × 4-min intervals running at 85-95% VO2max separated by 2-min active rest at 55-60% VO2max), 3 days/week for 8 weeks. Muscle fiber cross-sectional area (CSA) and the expression of signal transduction pathway proteins were determined in the gastrocnemius muscle.

Results

In the HIIT group, the expression of IGF-I, IGF-IR Akt, p-Akt, AMPKα, p-AMPKα and follistatin increased significantly, whereas a significant decrease was observed in the expression of FoxO1, p-FoxO1, myostatin, ActRIIB, Smad2/3 and p-Smad2/3 (P < 0.05). However, there were no significant differences between the HIIT and control groups in the expression of mTOR, p-mTOR, P70S6K, and p-P70S6K (P > 0.05). In addition, CSA and gastrocnemius muscle weight increased significantly in the HIIT group (P < 0.05).

Conclusions

HIIT induced muscle hypertrophy by improving IGF-I/Akt/FoxO and myostatin/Smad signal transduction pathways.

Resistance training attenuates circulating FGF-21 and myostatin and improves insulin resistance in elderly men with and without type 2 diabetes mellitus: A randomised controlled clinical trial

Fibroblast growth factor 21 (FGF-21) and myostatin have been proposed to be potential therapeutic target for insulin resistance in age-related metabolic disorders including type 2 diabetes (T2D). Moreover, despite the potential metabolic effect of resistance training on insulin resistance, aging, and T2D; the effect of this type of exercise training on FGF-21 and myostatin in elderly men with and without T2D are unknown. Forty-four elderly men were assigned to either the RT training (RT; without T2D: 12, with TD2 = 10) or the control group (C; without T2D: 12, with TD2 = 10). The RT group performed 12-wk resistance training intervention, 3 days/wk, 10 repetitions with 70% 1RM. At the baseline, the elderly men with T2D had a higher FGF-21 (p = 0.002) and myostatin (p = 0.02) concentrations and lower muscle strength (p = 0.01) than the elderly men without T2D. RT resulted in significant decrease in FGF-21 and myostatin concentration and increase in muscle strength in both elderly men with and without T2D (P = 0.001, for all) as well as decrease in HOMA-IR in only elderly men without T2D (P = 0.001). There was no significant difference in the RT-induced FGF-21 reduction between elderly men with and without T2D (p = 0.77, p = 0.28, respectively), but, RT caused a larger reduction in circulating myostatin in elderly men without T2D than with T2D (P = 0.007). Taken together, our results demonstrated that 12 weeks of RT induced an overall significant reduction of FGF-21 and myostatin in elderly men with and without T2D; with higher reduction of myostatin in elderly men without T2D.