Nicotine exacerbates exertional heat strain in trained men: a randomized, placebo-controlled, double-blind study.

To determine whether using nicotine exacerbates exertional heat strain through an increased metabolic heat production (Hprod) or decreased skin blood flow (SkBF), 10 nicotine-naïve trained males [37 ± 12 yr; peak oxygen consumption (V̇o2peak): 66 ± 10 mL·min-1·kg-1] completed four trials at 20°C and 30°C following overnight transdermal nicotine (7 mg·24 h-1) and placebo use in a crossover, double-blind design. They cycled for 60 min (55% V̇o2peak) followed by a time trial (∼75% V̇o2peak) during which measures of gastrointestinal (Tgi) and mean weighted skin ([Formula: see text]sk) temperatures, SkBF, Hprod, and mean arterial pressure (MAP) were made. The difference in ΔTgi between nicotine and placebo trials was greater during 30°C (0.4 ± 0.5°C) than 20°C (0.1 ± 0.7°C), with [Formula: see text]sk higher during nicotine than placebo trials (0.5 ± 0.5°C, P = 0.02). SkBF became progressively lower during nicotine than placebo trials (P = 0.01) and progressively higher during 30°C than 20°C trials (P < 0.01); MAP increased from baseline (P < 0.01) and remained elevated in all trials. The difference in Hprod between 30°C and 20°C trials was lower during nicotine than placebo (P = 0.01) and became progressively higher during 30°C than 20°C trials with exercise duration (P = 0.03). Mean power output during the time trial was lower during 30°C than 20°C trials (24 ± 25 W, P = 0.02), and although no effect of nicotine was observed (P > 0.59), two participants (20%) were unable to complete their 30°C nicotine trials as one reached the ethical limit for Tgi (40.0°C), whereas the other withdrew due to "nausea and chills" (Tgi = 39.7°C). These results demonstrate that nicotine use increases thermal strain and risk of exertional heat exhaustion by reducing SkBF.NEW & NOTEWORTHY In naïve participants, acute nicotine use exerts a hyperthermic effect that increases the risk of heat exhaustion during exertional heat strain, which is driven by a blunted skin blood flow response. This has implications for 1) populations that face exertional heat strain and demonstrate high nicotine use (e.g., athletes and military, 25%-50%) and 2) study design whereby screening and exclusion for nicotine use or standardization of prior use (e.g., overnight abstinence) is encouraged.

Effects of bovine whey protein on exercise-induced gut permeability in healthy adults: a randomised controlled trial.

PURPOSE: Intestinal permeability is a critical component of gut barrier function. Barrier dysfunction can be triggered by certain stressors such as exercise, and if left unmanaged can lead to local and systemic disorders. The aim of this study was to investigate the effects of a specific whey protein fraction in alleviating exercise-induced gut permeability as assessed by recovery of lactulose/rhamnose (L/R) and lactulose/mannitol (L/M) urinary probes. METHODS: Eight males and eight females (aged 18-50) completed two arms of a double-blind, placebo-controlled, crossover study. For each arm participants performed two baseline intestinal permeability assessments, following which they consumed the treatment (2 g/day of milk powder containing 200 mg of whey protein) or placebo (2 g/day of milk powder) for 14 days, before performing a post-exercise permeability assessment. The exercise protocol involved a 20-min run at 80% of maximal oxygen uptake on a 1% incline. RESULTS: Mixed model analysis revealed an increase in L/R (23%; P < 0.001) and L/M (20%; P < 0.01) recovery following exercise. However, there was no treatment or treatment × exercise effect. CONCLUSION: The exercise protocol utilised in our study induces gut permeability. However, consuming whey protein, at the dose and timing prescribed, is not able to mitigate this effect.

Nutrition-Based Strategies to Reduce Exercise-Induced Muscle Damage and Soreness.

Exercise induced-muscle damage (EIMD) occurs after strenuous and/or novel exercise that involves repeated eccentric contractions [...].

A comparison of the effects of sheep's milk and cow's milk on recovery from eccentric exercise.

Introduction: When consumed after eccentric exercise, cow's milk has been shown to improve recovery and alleviate symptoms of exercise induced muscle damage. Although currently less commercially available than cow's milk, sheep's milk may offer similar or greater benefits for recovery as it is higher in protein and energy; however, the effect of sheep's milk in any exercise context has not been explored. This study compared the effects of a sheep's milk beverage and a cow's milk beverage on recovery from strenuous eccentric exercise. Additionally, the effects of each beverage on satiety and gastrointestinal comfort were assessed. Methods: Ten healthy males completed baseline measures of perceived muscle soreness and maximal voluntary concentric, eccentric, and isometric quadriceps force of one leg before completing 200 maximal eccentric knee extensions on an isokinetic dynamometer. Measures were repeated 0.5, 24, 48 and 72 h post-eccentric exercise. After 0.5 h measures, participants consumed either 450 ml of chocolate flavored sheep's milk or chocolate flavored cow's milk. Following a washout period, participants completed a second trial on the contralateral leg and consumed the other beverage. Additionally, a satiety and gastrointestinal comfort questionnaire was completed before and after each beverage was consumed. Results: Eccentric exercise brought about a significant decrease in muscle function over time (all P < 0.012). No difference between treatments (all P > 0.097) was found. Measures of muscle soreness increased over time (all P < 0.002), however no difference was observed between treatments (all P > 0.072). Only sheep's milk altered perceived satiety, however, only the response to "How full do you feel" differed between treatments (P = 0.04). Discussion: The results of this study suggest that consuming sheep's milk may provide similar benefits as cow's milk when recovering from exercise-induced muscle damage. While these findings provide initial support for the use of sheep's milk in a muscle recovery context, further research is warranted to confirm these findings. Given its superior nutritional profile, greater impact on satiety and lower environment impact, sheep's milk may be a more efficient post-exercise recovery beverage, compared to cow's milk.

Nutritional Compounds to Improve Post-Exercise Recovery.

The metabolic and mechanical stresses associated with muscle-fatiguing exercise result in perturbations to bodily tissues that lead to exercise-induced muscle damage (EIMD), a state of fatigue involving oxidative stress and inflammation that is accompanied by muscle weakness, pain and a reduced ability to perform subsequent training sessions or competitions. This review collates evidence from previous research on a wide range of nutritional compounds that have the potential to speed up post-exercise recovery. We show that of the numerous compounds investigated thus far, only two-tart cherry and omega-3 fatty acids-are supported by substantial research evidence. Further studies are required to clarify the potential effects of other compounds presented here, many of which have been used since ancient times to treat conditions associated with inflammation and disease.

An experimental model of contusion injury in humans.

INTRODUCTION: Contusion injuries are common in sport, but our knowledge of the responses to injury primarily come from animal studies and research using eccentric exercise. Therefore, the aim of this study was to develop a model of contusion injury in human participants and, additionally, investigate and compare physiological responses to four impact loads. METHODS: Thirty-two males were exposed to a single impact of either 4.2, 5.2, 6.2 or 7.2kg, dropped from 67 cm, on to the vastus lateralis of one leg. Maximum voluntary and electrically induced quadriceps force, and pressure pain threshold were measured, and blood sampling carried out, prior to and 30min, 24, 48 and 72h post-impact. Magnetic resonance imaging was carried out 24h post-impact to quantify oedema. RESULTS: Despite impact force with 7.2kg (1681.4 ± 235.6 N) not being different to 6.2kg (1690.7 ± 117.6 N), 7.2kg resulted in greater volume of oedema, voluntary force loss, pain and elevations in creatine kinase than the other loads. Although electrically induced force changed over time, post-hoc analysis failed to identify any changes. Interleukin-6 and prostaglandin-E2 did not change over time for any of the loads. Significant correlations were found between oedema volume, pressure pain threshold and maximum voluntary contraction force. CONCLUSIONS: This is the first experimental study to investigate traumatic loading of skeletal muscle and the subsequent physiological responses associated with contusion injuries in humans. The absence of immediate elevations in creatine kinase and changes in electrically induced force suggest impact, with forces similar to those experienced in contact sport, does not cause significant, direct damage to skeletal muscle. However, the relationship between oedema volume, changes in pressure pain threshold and maximum voluntary contraction force suggests central inhibition plays a role in contusion-related muscle dysfunction.

Astragalosides Supplementation Enhances Intrinsic Muscle Repair Capacity Following Eccentric Exercise-Induced Injury.

Astragalosides have been shown to enhance endurance exercise capacity in vivo and promote muscular hypertrophy in vitro. However, it remains unknown whether astragalosides supplementation can alter inflammatory response and enhance muscle recovery after damage in humans. We therefore aimed to evaluate the effect of astragalosides supplementation on muscle's intrinsic capacity to regenerate and repair itself after exercise-induced damage. Using a randomized double-blind placebo-controlled cross-over design, eleven male participants underwent 7 days of astragalosides supplementation (in total containing 4 mg of astragalosides per day) or a placebo control, following an eccentric exercise protocol. Serum blood samples and variables related to muscle function were collected prior to and immediately following the muscle damage protocol and also at 2 h, and 1, 2, 3, 5, and 7 days of the recovery period, to assess the pro-inflammatory cytokine response, the secretion of muscle regenerative factors, and muscular strength. Astragalosides supplementation reduced biomarkers of skeletal muscle damage (serum CK, LDH, and Mb), when compared to the placebo, at 1, 2, and 3 days following the muscle damage protocol. Astragalosides supplementation suppressed the secretion of IL-6 and TNF-α, whilst increasing the release of IGF-1 during the initial stages of muscle recovery. Furthermore, following astragaloside supplementation, muscular strength returned to baseline 2 days earlier than the placebo. Astragalosides supplementation shortens the duration of inflammation, enhances the regeneration process and restores muscle strength following eccentric exercise-induced injury.

Peak Power Output and Onset of Muscle Activation During High Pull Exercise.

ABSTRACT: Barnes, MJ, Petterson, A, and Cochrane, DJ. Peak power output and onset of muscle activation during high pull exercise. J Strength Cond Res 35(3): 675-679, 2021-The aim of this study was to determine the percentage of 1 repetition maximum (1RM) at which peak power output occurred during the high pull (HP) exercise. In addition, the onset time of the biceps femoris (BF) and gluteus maximus (GM), across a range of loads, was investigated. Twelve resistance-trained men performed 1RM testing for the HP followed by lifts at 10% increments from 30 to 80% 1RM. During each load of power, output was measured using a linear potentiometer, whereas surface electromyography was recorded from the BF and GM. Peak power output occurred at 70% (1881.9 ± 296.1 W); however, there was no significant difference between loads at 60-80% (all p > 0.05). Loads between 40 and 80% 1RM produced significantly higher power outputs than 30% while 80% generated greater power than 100% 1RM (all p < 0.05). There was no significant (p > 0.05) main effect of muscle or load in the onset of BF (156.5-212.1 ms) or GM (112.1-158.1 ms). Therefore, these results suggest that training at a load between 60 and 80% 1RM may be useful in increasing power in the HP. In addition, activation of 2 of the hip extensors occurs in a relatively synchronous order irrespective of load.

Anthocyanin-Rich New Zealand Blackcurrant Extract Supports the Maintenance of Forearm Blood-Flow During Prolonged Sedentary Sitting.

Objectives: We examined the acute effects of anthocyanin-rich New Zealand blackcurrant extract and a placebo on hemodynamics during 120 min of sedentary sitting in healthy males. Additionally, we investigated whether changes in resting hemodynamics altered repeated isometric hand-grip exercise performance and post exercise forearm blood flow (FBF). Methods: Ten healthy males completed two trials during which they ingested either blackcurrant extract (1.87 mg total anthocyanins/kg bodyweight) or placebo powder. Heart rate, blood pressure and forearm blood flow were measured, and venous blood was sampled, prior to and 30, 60, 90 and 120 min-post ingestion. Participants remained seated for the duration of each trial. At 120 min post-ingestion participants completed as many repetitions of isometric hand-grip contractions as possible. Results: Heart rate, blood pressure and mean arterial pressure changed over time (all p < 0.001) but did not differ between treatments. A treatment x time interaction for FBF (p = 0.025) and forearm vascular resistance (FVR) (p = 0.002) was found. No difference in the number of isometric hand-grip contractions was observed between treatments (p = 0.68) nor was there any treatment x time interaction in post-exercise FBF (p = 0.997). Plasma endothelin-1 (p = 0.023) and nitrate (p = 0.047) changed over time but did not differ between treatments (both p > 0.1). Plasma nitrite did not change over time (p = 0.732) or differ between treatments (p = 0.373). Conclusion: This study demonstrated that acute ingestion of a single dose of blackcurrant extract maintained FBF and FVR during an extended period of sitting; however, this did not influence exercise performance during hand-grip exercise.

Nicotine Supplementation Does Not Influence Performance of a 1h Cycling Time-Trial in Trained Males.

The use of nicotine amongst professional and elite athletes is high, with anecdotal evidence indicating increased prevalence amongst cycling sports. However, previous investigations into its effects on performance have not used high-validity or -reliability protocols nor trained cyclists. Therefore, the present study determined whether nicotine administration proved ergogenic during a ∼1 h self-paced cycling time-trial (TT). Ten well-trained male cyclists (34 ± 9 years; 71 ± 8 kg; O2max: 71 ± 6 ml ⋅ kg-1 ⋅ min-1) completed three work-dependent TT following ∼30 min administration of 2 mg nicotine gum (GUM), ∼10 h administration of 7 mg ⋅ 24 h-1 nicotine patch (PAT) or color- and flavor-matched placebos (PLA) in a randomized, crossover, and double blind design. Measures of nicotine's primary metabolite (cotinine), core body temperature, heart rate, blood biochemistry (pH, HCO3 -, La-) and Borg's rating of perceived exertion (RPE) accompanied performance measures of time and power output. Plasma concentrations of cotinine were highest for PAT, followed by GUM, then PLA, respectively (p < 0.01). GUM and PAT resulted in no significant improvement in performance time compared to PLA (62.9 ± 4.1 min, 62.6 ± 4.5 min, and 63.3 ± 4.1 min, respectively; p = 0.73), with mean power outputs of 264 ± 31, 265 ± 32, and 263 ± 33 W, respectively (p = 0.74). Core body temperature was similar between trials (p = 0.33) whilst HR averaged 170 ± 10, 170 ± 11, and 171 ± 11 beats ⋅ min-1 (p = 0.60) for GUM, PAT, and PLA, respectively. There were no differences between trials for any blood biochemistry (all p > 0.46) or RPE with mean values of 16.7 ± 0.9, 16.8 ± 0.7, and 16.8 ± 0.8 (p = 0.89) for GUM, PAT, and PLA, respectively. In conclusion: (i) nicotine administration, whether via gum or transdermal patch, did not exert an ergogenic or ergolytic effect on self-paced cycling performance of ∼1 h; (ii) systemic delivery of nicotine was greatest when using a transdermal patch; and (iii) nicotine administration did not alter any of the psycho-physiological measures observed.

On exercise thermoregulation in females: interaction of endogenous and exogenous ovarian hormones.

KEY POINTS: One in two female athletes chronically take a combined, monophasic oral contraceptive pill (OCP). Previous thermoregulatory investigations proposed that an endogenous rhythm of the menstrual cycle still occurs with OCP usage. Forthcoming large international sporting events will expose female athletes to hot environments differing in their thermal profile, yet few data exist on how trained women will respond from both a thermoregulatory and performance stand-point. In the present study, we have demonstrated that a small endogenous rhythm of the menstrual cycle still affects Tcore and also that chronic OCP use attenuates the sweating response, whereas behavioural thermoregulation is maintained. Furthermore, humid heat affects both performance and thermoregulatory responses to a greater extent than OCP usage and the menstrual cycle does. ABSTRACT: We studied thermoregulatory responses of ten well-trained ( V̇O2max , 57 ± 7 mL min-1  kg-1 ) women taking a combined, monophasic oral contraceptive pill (OCP) (≥12 months) during exercise in dry and humid heat, across their active OCP cycle. They completed four trials, each of resting and cycling at fixed intensities (125 and 150 W), aiming to assess autonomic regulation, and then a self-paced intensity (30-min work trial) to assess behavioural regulation. Trials were conducted in quasi-follicular (qF) and quasi-luteal (qL) phases in dry (DRY) and humid (HUM) heat matched for wet bulb globe temperature (WBGT) (27°C). During rest and exercise at 125 W, rectal temperature was 0.15°C higher in qL than qF (P = 0.05) independent of environment (P = 0.17). The onset threshold and thermosensitivity of local sweat rate and forearm blood flow relative to mean body temperature was unaffected by the OCP cycle (both P > 0.30). Exercise performance did not differ between quasi-phases (qF: 268 ± 31 kJ, qL: 263 ± 26 kJ, P = 0.31) but was 5 ± 7% higher during DRY than during HUM (273 ± 29 kJ, 258 ± 28 kJ; P = 0.03). Compared to matched eumenorrhoeic athletes, chronic OCP use impaired the sweating onset threshold and thermosensitivity (both P < 0.01). In well-trained, OCP-using women exercising in the heat: (i) a performance-thermoregulatory trade-off occurred that required behavioural adjustment; (ii) humidity impaired performance as a result of reduced evaporative power despite matched WBGT; and (iii) the sudomotor but not behavioural thermoregulatory responses were impaired compared to matched eumenorrhoeic athletes.

Muscle activation and local muscular fatigue during a 12-minute rotational bridge.

Due to anecdotal reports of back pain during a 12-minute rotational bridge test by uniformed services, the level of fatigue leading to possible back pain and or injury was investigated. We hypothesised a high level of fatigue due to diminishing core muscle activation. Nineteen highly trained uniformed service members were measured by surface electromyography of the rectus abdominis, external oblique, internal oblique, lumbar erector spinae, thoracic erector spinae and latissimus dorsi. Average rectified electromyography amplitude (AEMG) and median power frequency were analysed to determine activation and fatigue. All AEMG were normalised and expressed as a percentage of maximal voluntary isometric contraction (%MVIC). Significant increases in AEMG were observed over the test duration for the rectus abdominis (+19.5%MVIC), external oblique (+18.0%MVIC) and internal oblique (+23.2%MVIC) during the prone position; and for the external oblique (+21.8%MVIC) when bracing on the measurement side (all, p < 0.05). No significant changes in median power frequency were observed (all, p > 0.05). Combining prone and side bridge positions is a reasonable measure of anterior, posterior and lateral trunk musculature. Muscular fatigue remained low throughout making this a safe assessment in trained individuals.

Acute Neuromuscular and Endocrine Responses to Two Different Compound Exercises: Squat vs. Deadlift.

Barnes, MJ, Miller, A, Reeve, D, and Stewart, RJ. Acute neuromuscular and endocrine responses to two different compound exercises: squat vs. deadlift. J Strength Cond Res 33(9): 2381-2387, 2019-Anecdotally, it is believed that the deadlift exercise brings about greater levels of central fatigue than other exercises; however, no empirical evidence exists to support this view. In addition, little is known about the acute endocrine response to heavy deadlift exercise and how this may differ from other similar compound exercises. Therefore, the aim of this study was to identify and compare the acute, neuromuscular and endocrine responses to squat and deadlift exercises. Ten resistance-trained males completed 8 sets of 2 repetitions at 95% of 1 repetition maximum. Maximum voluntary isometric contraction (MVIC) force of the quadriceps, along with measures of central (voluntary activation [VA] and surface electromyography) and peripheral (electrically evoked control stimulus) fatigue were made before and 5 and 30 minutes after exercise. In addition, salivary testosterone and cortisol were measured at these same time points. MVIC was reduced after the completion of both exercises (p = 0.007); however, no difference between exercises was evident. Similarly, although VA changed over time (p = 0.0001), no difference was observed between exercises. As a measure of peripheral fatigue, force from the control stimulus changed over time (p = 0.003) with a greater decrease evident after the squat (p = 0.034). Electromyography was reduced over time (p = 0.048) but no difference was seen between exercises. No change was seen in testosterone and cortisol. Although a greater absolute load and larger volume load were completed for the deadlift, no difference in central fatigue was evident between the 2 compound exercises. The greater peripheral fatigue observed after squat exercise may be due to the greater work completed by the quadriceps with this exercise. These results suggest that separate periodization, tapering, and programming considerations may be unnecessary when using the squat and deadlift to develop muscular strength.

Higher- Versus Lower-Intensity Strength-Training Taper: Effects on Neuromuscular Performance.

PURPOSE: To investigate the effects of strength-training tapers of different intensities but equal volume reductions on neuromuscular performance. METHODS: Eleven strength-trained men (21.3 [3.3] y, 92.3 [17.6] kg, relative 1-repetition-maximum deadlift 1.9 [0.2] times bodyweight) completed a crossover study. Specifically, two 4-wk strength-training blocks were followed by a taper week with reduced volume (∼70%) involving either increased (5.9%) or decreased (-8.5%) intensity. Testing occurred pretraining (T1), posttraining (T2), and posttaper (T3). Salivary testosterone and cortisol, plasma creatine kinase, a Daily Analysis of Life Demands in Athletes questionnaire, countermovement jump (CMJ), isometric midthigh pull, and isometric bench press were measured. RESULTS: CMJ height improved significantly over time (P < .001), with significant increases from T1 (38.0 [5.5] cm) to both T2 (39.3 [5.3] cm; P = .010) and T3 (40.0 [5.3] cm; P = .001) and from T2 to T3 (P = .002). CMJ flight time:contraction time increased significantly over time (P = .004), with significant increases from T1 (0.747 [0.162]) to T2 (0.791 [0.163]; P = .012). Isometric midthigh-pull relative peak force improved significantly over time (P = .033), with significant increases from T1 (34.7 [5.0] N/kg) to T2 (35.9 [4.8] N/kg; P = .013). No significant changes were found between tapers. However, the higher-intensity taper produced small effect-size increases at T3 vs T1 for isometric midthigh-pull relative peak force, CMJ height, and flight time:contraction time, while the lower-intensity taper only produced small effect-size improvements at T3 vs T1 for CMJ height. CONCLUSIONS: A strength-training taper with volume reductions had a positive effect on power, with a tendency for the higher-intensity taper to produce more favorable changes in strength and power.

Is Postexercise Blood Flow Restriction a Viable Alternative to Other Resistance Exercise Protocols?

PURPOSE: The purpose of this study was to identify whether post-resistance exercise (REx) blood flow restriction (BFR) can elicit a similar acute training stimulus to that offered by either heavy REx or traditional low-load BFR REx. METHOD: Ten men completed trials with 30% one-repetition maximum (1RM) for 5 sets of 15 repetitions without BFR (30%), with BFR during exercise (30% RD), and with postexercise BFR (30% RP) and at 75% 1RM for 3 sets of 10 repetitions. Lactate and cortisol were measured before and up to 60 min after exercise. Thigh circumference, ratings of perceived exertion (RPE), and pain were measured before and after exercise. Surface electromyography was measured during exercise. RESULTS: All conditions had a large effect (effect size [ES] > 0.8) on lactate, with the largest effects observed with the 75% condition; no differences were observed between the 30% conditions. All conditions had a moderate effect (ES > 0.25 ≤ 0.4) on increasing thigh circumference. This effect was maintained (ES = 0.35) with the application of BFR after REx (30% RP). Change in RPE, from the first to last set, was significantly greater with 30% RD compared with other conditions (all p < .05). Electromyography amplitude was higher and percentage change was greater for the 75% condition compared with the other conditions (both p < .05). CONCLUSIONS: The application of BFR immediately post-REx altered several of the responses associated with REx that is aimed at inducing muscular hypertrophy. Additionally, these changes occurred with less pain and perceived exertion suggesting that this form of REx may offer an alternative, tolerable method of REx.

The effect of chronic soluble keratin supplementation in physically active individuals on body composition, blood parameters and cycling performance.

BACKGROUND: Keratins are structural, thiol-rich proteins, which comprise 90% of total poultry feather weight. Their favourable amino acid profile suggests the potential for use as a protein source and ergogenic aid for endurance athletes, following treatment to increase digestibility. This study investigated whether 4 weeks of soluble keratin (KER) consumption (0.8 g/kg bodyweight/day) by 15 endurance-trained males would have favourable effects on body composition, blood and cardiorespiratory variables, and cycling performance, compared to casein protein (CAS). METHODS: Supplementation was randomized, blinded and balanced, with a minimum eight-week washout period between trials. An exercise test to measure oxygen consumption during submaximal and maximal cycling exercise was completed at the start at and end of each intervention. Anthropometric (DEXA) and blood measures were made prior to and following each intervention period. RESULTS: Total body mass and percentage body fat did not change significantly (p > 0.05). However, a significantly greater increase in bone-free lean mass (LM) occurred with KER compared to CAS (0.88 kg vs 0.07 kg; p < 0.05). While no change in LM was evident for the trunk and arms, leg LM increased (0.45 ± 0.54 kg; p = 0.006) from baseline with KER. KER was not associated with changes in blood parameters, oxygen consumption, or exercise performance (p > 0.05). CONCLUSIONS: These data suggest that KER is not useful as an ergogenic aid for endurance athletes but may be a suitable protein supplement for maximizing increases in lean body mass.

Multiday Pomegranate Extract Supplementation Decreases Oxygen Uptake During Submaximal Cycling Exercise, but Cosupplementation With N-acetylcysteine Negates the Effect.

Pomegranate extract (POMx) has been suggested as an ergogenic aid due to its rich concentration of polyphenols, which are proposed to enhance nitric oxide bioavailability, thereby improving the efficiency of oxygen usage and, consequently, endurance exercise performance. Although acute POMx supplementation improves aerobic exercise performance in untrained individuals, trained athletes appear to require chronic supplementation for a similar effect. Furthermore, the combination of POMx with a thiol antioxidant may prove more effective than POMx alone, due to the protective effects of thiols on nitric oxide. Thus, this study hypothesized that multiday POMx supplementation would decrease the oxygen uptake (VO2) required by trained cyclists to perform submaximal exercise and increase performance during a time trial, and that thiol (N-acetylcysteine [NAC]) cosupplementation would enhance these effects. Eight cyclists completed four 8-day supplementation periods: POMx only, NAC only, POMx + NAC (BOTH), and placebo. Following supplementation, they performed submaximal cycling and a 5-min time trial, with VO2 and muscle oxygen saturation (SmO2) being recorded. A three-way (POMx × NAC × Intensity) repeated-measures analysis of variance with a Fisher's least significant difference post hoc assessment was performed for dependent variables (p ≤ .05). VO2 during submaximal exercise was reduced with POMx versus placebo (-2.6 ml·min-1·kg-1, p = .009) and BOTH (-2.5 ml·min-1·kg-1, p < .05) and increased with NAC (+1.9 ml·min-1·kg-1, p < .03), despite no main effect of treatment on SmO2 or performance. It appears that POMx's high polyphenol content reduced the VO2 required during submaximal exercise. However, NAC cosupplementation annulled this effect; thus, NAC may interact with nitric oxide to reduce its bioavailability.

Short-Term Training Cessation as a Method of Tapering to Improve Maximal Strength.

Pritchard, HJ, Barnes, MJ, Stewart, RJC, Keogh, JWL, and McGuigan, MR. Short-term training cessation as a method of tapering to improve maximal strength. J Strength Cond Res 32(2): 458-465, 2018-The aim of this study was to determine the effects of 2 different durations of training cessation on upper- and lower-body maximal strength performance and to investigate the mechanisms underlying performance changes following short-term training cessation. Eight resistance trained males (23.8 ± 5.4 years, 79.6 ± 10.2 kg, 1.80 ± 0.06 m, relative deadlift 1 repetition maximum of 1.90 ± 0.30 times bodyweight [BW]) each completed two 4-week strength training periods followed by either 3.5 days (3.68 ± 0.12 days) or 5.5 days (5.71 ± 0.13 days) of training cessation. Testing occurred pretraining (T1), on the final day of training (T2), and after each respective period of training cessation (T3). Participants were tested for salivary testosterone and cortisol, plasma creatine kinase, psychological profiles, and performance tests (countermovement jump [CMJ], isometric midthigh pull, and isometric bench press [IBP]) on a force plate. Participants' BW increased significantly over time (p = 0.022). The CMJ height and IBP peak force showed significant increases over time (p = 0.013, 0.048, and 0.004, respectively). Post hoc testing showed a significant increase between T1 and T3 for both CMJ height and IBP peak force (p = 0.022 and 0.008 with effect sizes of 0.30 and 0.21, respectively). No other significant differences were seen for any other measures. These results suggest that a short period of strength training cessation can have positive effects on maximal strength expression, perhaps because of decreases in neuromuscular fatigue.

A Randomised, Placebo-Controlled, Crossover Study Investigating the Effects of Nicotine Gum on Strength, Power and Anaerobic Performance in Nicotine-Naïve, Active Males.

BACKGROUND: Nicotine use amongst athletes is high and increasing, especially team sports, yet the limited previous studies investigating the performance consequences of this behaviour have not examined the effects of the principal active ingredient, nicotine, per se. Therefore, we determined whether nicotine gum affected muscular and anaerobic performance. METHODS: Nine active males (24 ± 3 years) completed three trials in a random order in which 20 min prior to testing they chewed 2 mg (NIC-2), 4 mg (NIC-4) nicotine or flavour-matched placebo (PLA) gum. Peak and average peak isometric, concentric and eccentric leg extensor torque was measured followed by vertical counter-movement jump height and a 30-s Wingate test. Heart rate was measured whilst capillary blood samples determined pH, HCO3- and venous blood confirmed the presence of nicotine. RESULTS: Nicotine was confirmed by the presence of its major metabolite, cotinine and participants reported no side effects with nicotine. Peak and average peak isometric and eccentric torque was significantly affected (NIC-2 > PLA; p < 0.05) whilst peak (NIC-2 > PLA; p < 0.05) but not average peak (p > 0.05) concentric torque was different between trials. Counter-movement jump height was similar across trials (p > 0.05). Anaerobic capacity during the Wingate remained similar across trials (p > 0.05); however, pacing strategy (peak power and rate of fatigue) was different during NIC-2 than PLA. pH was affected by nicotine (NIC-2 > PLA; p < 0.05) and was reduced following the Wingate in all trials. HCO3- showed similar responses across trials (p > 0.05) although it was also reduced following the Wingate (p < 0.05), whilst heart rate was significantly affected (NIC-2/NIC-4 > PLA; p < 0.05). CONCLUSIONS: Chewing low-dose (2 mg) nicotine gum 20 min prior to exercise significantly improved leg extensor torque but did not affect counter-movement jump height or Wingate performance compared to a placebo, whilst there were minimal effects of the 4 mg nicotine gum on the performance parameters measured.