https://cyberleninka.org/article/n/662127.pdf

A review of caffeine's effects on cognitive, physical and occupational performance.

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

https://www.mdpi.com/1424-8220/20/21/6396/pdf

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

The need to quantify aspects of training to improve training prescription has been the holy grail of sport scientists and coaches for many years. Recently, there has been an increase in scientific interest, possibly due to technological advancements and better equipment to quantify training activities. Over the last few years there has been an increase in the number of studies assessing training load in various athletic cohorts with a bias toward subjective reports and/or quantifications of external load. There is an evident lack of extensive longitudinal studies employing objective internal-load measurements, possibly due to the cost-effectiveness and invasiveness of measures necessary to quantify objective internal loads. Advances in technology might help in developing better wearable tools able to ease the difficulties and costs associated with conducting longitudinal observational studies in athletic cohorts and possibly provide better information on the biological implications of specific external-lo...

https://journals.humankinetics.com/downloadpdf/journals/ijspp/12/s2/article-pS2-55.pdf

Wearable Training-Monitoring Technology: Applications, Challenges, and Opportunities.

PALLARES, J. G., V. E. FERNANDEZ-ELIAS, J. F. ORTEGA, G. MUNOZ, J. MUNOZ-GUERRA, and R. MORA-RODRIGUEZ. Neuromuscular Responses to Incremental Caffeine Doses: Performance and Side Effects. Med. Sci. Sports Exerc., Vol. 45, No. 11, pp. 2184-2192, 2013. Purpose: The purpose of this study was to determine the oral dose of caffeine needed to increase muscle force and power output during all-out single multijoint movements. Methods: Thirteen resistance-trained men underwent a battery of muscle strength and power tests in a randomized, double-blind, crossover design, under four different conditions: (a) placebo ingestion (PLAC) or with caffeine ingestion at doses of (b) 3 mgIkg j1 body weight (CAFF3mg), (c) 6 mgIkg j1 (CAFF6mg), and (d) 9 mgIkg j1 (CAFF9mg). The muscle strength and power tests consisted in the measurement of bar displacement velocity and muscle power output during free- weight full-squat (SQ) and bench press (BP) exercises against four incremental loads (25%, 50%, 75%, and 90% one-repetition maxi- mum (1RM)). Cycling peak power output was measured using a 4-s inertial load test. Caffeine side effects were evaluated at the end of each trial and 24 h later. Results: Mean propulsive velocity at light loads (25%-50% 1RM) increased significantly above PLAC for all caffeine doses (5.4%-8.5%, P = 0.039-0.003). At the medium load (75% 1RM), CAFF3mg did not improve SQ or BP muscle power or BP velocity. CAFF9mg was needed to enhance BP velocity and SQ power at the heaviest load (90% 1RM) and cycling peak power output (6.8%-11.7%, P = 0.03-0.05). The CAFF9mg trial drastically increased the frequency of the adverse side effects (15%-62%). Conclusions: The ergogenic dose of caffeine required to enhance neuromuscular performance during a single all-out contraction depends on the magnitude of load used. A dose of 3 mgIkg j1 is enough to improve high-velocity muscle actions against low loads, whereas a higher

Neuromuscular responses to incremental caffeine doses: performance and side effects.

Caffeine-containing energy drinks (EDs) are currently used as ergogenic aids to improve physical performance in a wide variety of sport disciplines. However, the outcomes of previous investigations on this topic are inconclusive due to methodological differences, especially, in the dosage of the active ingredients and the test used to assess performance. We performed a systematic review and meta-analysis of published studies to evaluate the effects of acute ED intake on physical performance. The search for references was conducted in the databases PubMed, ISI Web of Knowledge and SPORTDiscus until December 2015. Thirty-four studies published between 1998 and 2015 were included in the analysis. Using a random-effects model, effect sizes (ES) were calculated as the standardized mean difference. Overall, ED ingestion improved physical performance in muscle strength and endurance (ES = 0.49; p < 0.001), endurance exercise tests (ES = 0.53; p < 0.001), jumping (ES = 0.29; p = 0.01) and sport-specific actions (ES = 0.51; p < 0.001), but not in sprinting (ES = 0.14; p = 0.06). The meta-regression demonstrated a significant association between taurine dosage (mg) and performance (slope = 0.0001; p = 0.04), but not between caffeine dosage (mg) and performance (slope = 0.0009; p = 0.21).
 ED ingestion improved performance in muscle strength and endurance, endurance exercise tests, jumping and sport-specific actions. However, the improvement in performance was associated with taurine dosage.

Acute effects of caffeine-containing energy drinks on physical performance: a systematic review and meta-analysis.

Introduction: In this study we tested the hypothe- sis that caffeine supplementation improves neuromuscular func- tion, which has both nutritional and clinical relevance. Methods: Fourteen male subjects (mean 6 SD: 23.8 6 2.8 years) volun- teered in a double-blind, repeated-measures study with placebo (PLA) or caffeine (CAFF) (6 mg kg � 1 ). Maximal voluntary iso- metric contractions (MVCs), evoked maximal twitch, and maxi- mal isokinetic contractions during elbow flexion were assessed. Mechanical and electromyographic (EMG) signals from the biceps brachii muscle were recorded, and muscle fiber conduc- tion velocity (CV) was calculated to evaluate changes in the muscle force-velocity relationship and muscle fiber recruitment. Results: The torque-angular velocity curve was enhanced after CAFF supplementation. This was supported by a concomitant increase of CV values (8.7% higher in CAFF). Conclusions: Caffeine improves muscle performance during short-duration maximal dynamic contractions. The concomitant improvement of mean fiber CV supports the hypothesis of an effect of caf- feine on motor unit recruitment. Muscle Nerve 000: 000-000, 2011

Caffeine improves neuromuscular function during maximal dynamic exercise.

Purpose:Variables currently used in soccer training monitoring fail to represent the physiological demand of the player during movements like accelerations, decelerations and directional changes pe...

Respiratory Frequency as a Marker of Physical Effort During High-Intensity Interval Training in Soccer Players

BACKGROUND The bulk of research investigating soccer player's performance has been concentrated on the metabolic demand, while only few studies focused on the neuromuscular activation. The present study aimed at investigating the activation profile of the leg muscles throughout a 90- minute soccer match. METHODS Fifteen football players (18.3±0.7 years) performed: 1) an isometric maximal voluntary contraction (MVC) before the game [MVCpre]; 2) a 90-minute soccer match (composed of two 45-minute periods separated by a 15-minute rest); 3) a second MVC after the match [MVCpost]. Electromyographic (EMG) activity of the Vastus Lateralis (VL) muscle of the dominant leg was recorded during the match. The root mean square (RMS) of the EMG signals was normalized for the maximal RMS obtained during the MVCpre (100%RMSmax) and six intensity classes were created in order to represent the %RMS distribution during the match (1st: 0-20%RMSmax; 2nd: 20-40%RMSmax; 3rd: 40-60%RMSmax; 4th: 60-80%RMSmax; 5th: 80-100%RMSmax; 6th: 100-120%RMSmax). RESULTS After the 90-minute soccer match, knee extensor MVC failed to show any statistical difference from pre-game values (-4.2%; P>0.05) whilst the neuromuscular activation demonstrated a significant reduction (-26.3%, P<0.01). During the game, the mean total distribution of RMS of the players was: 84.8±7.1% of total time in the 1st class, 8.5±3.9% in the 2nd, 3.6±1.6% in the 3rd, 1.7±1.0% in the 4th, 0.9±0.6% in the 5th and 0.4±0.5% in the 6th class of intensity. There was a significant difference (P<0.05) between the first versus the second half for the classes 1st, 3rd and 4th. CONCLUSIONS This represents the first attempt to characterize the neuromuscular activation profile during a 90-minute soccer match. Integrating this approach with more traditional ones may help further our understanding of the physiological demand of competitive soccer.

Marco Montini

Papers

Caffeine improves neuromuscular function during maximal dynamic exercise.

Respiratory Frequency as a Marker of Physical Effort During High-Intensity Interval Training in Soccer Players

Neuromuscular demand in a soccer match assessed by a continuous electromyographic recording.