Sport and Exercise Science PGR programme page. all accredited by the British Association of Sport and Exercise Sciences (BASES) and include: each student receives personal attention and guidance throughout their doctoral study. social life where our post-graduate research students build life-long relationships. athletes display many different types of disability and within a particular sport A variety of exercise testing modes can be used for the physiological assessment . To satisfy the muscle force-velocity relationships an optimal braking load is. Sport and Exercise Physiology Testing Guidelines: Volume II - Exercise and of Sport and Exercise Sciences Guide (Bases Sport and Exercise Science).
He and his wife of 55 years, Judy, have two daughters. Costill is a private pilot, auto and experimental airplane builder, competitive masters swimmer, and former marathon runner. Supplementary Instructional Materials All ancillary materials for this text are free to course adopters and available at www.
Includes sample lecture outlines, key points, and student assignments for every chapter in the text, along with sample laboratory exercises and direct links to a range of detailed sources on the Internet.
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The test package is available for use through multiple formats, including a learning management system, Respondus, and rich text. Contains 10 questions per chapter that instructors can use in their lessons to gauge student comprehension. Compatible with learning management systems, these quizzes offer easy grading and record keeping for instructors.
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Instructors will be able to access the animations from a centralized location for easy reference and use in classes and lectures. The animations are also included in the web study guide for student access.
Critical Power: An Important Fatigue Threshold in Exercise Physiology
Includes 29 videos from key leaders in the field discussing recent developments and real-world applications. Instructors will be able to view all video clips from a centralized location and incorporate them into classes and lectures.
The video clips are also included in the web study guide for student access. Instructors will be able to access all audio clips from a centralized location and incorporate them into classes and lectures.
The audio clips are also included in the web study guide for student access. Although a-vO2diff may improve with aerobic training [ 4950 ], the cellular mechanisms contributing to oxygen extraction within skeletal muscle also increase at a predictable rate during incremental to maximal exercise.
Recent meta-analyses by Montero et al. These studies concluded that the improvements in VO2max from 5 to 52 weeks of endurance training were due to linear improvements in Qmax but not a-vO2diff. Therefore, the peripheral mechanisms are viewed as a complement to the central mechanisms contributing to VO2max. In an attempt to investigate this issue, healthy males 18—35 years completed a wide range of GXT protocols under various conditions of physical stressors caloric restriction, bed rest, temperature, and illness.
Since then, there has been a search for an optimal standardized protocol suitable for the entire spectrum of fitness abilities and testing goals. The two modalities commonly used in GXT are treadmill and cycle ergometry. While the treadmill appears to be the most widely used modality due to familiarity with upright locomotion and greater muscle mass utilization, cycling protocols present an opportunity to test individuals with coordination or orthopedic limitations. Furthermore, opting to use a cycle ergometer over treadmill may result in a more quantifiable workload Watts and provides an opportunity to use a progressive ramp protocol allowing for more reproducible outcomes [ 9 ].
This difference is attributed to a larger recruitment of exercising skeletal muscle mass, Q and a-vO2diff, vascular conductance, and a lower rate of carbohydrate oxidation leading to a less severe development of metabolic acidosis at submaximal intensities [ 1556 — 60 ]. Realizing the need to investigate physiological responses to the earliest standardized GXT protocols, Pollock et al.
Journal of Exercise Science & Fitness - Elsevier
Balke [ 62 ], Bruce [ 63 ], Ellestad [ 64 ], and modified Astrand [ 65 ]. Each test differed in the method of increasing work rate in a step fashion either speed or grade.
The Balke protocol maintains a constant speed 3. The Bruce protocol increases speed and grade every 3 min. Finally, the Astrand protocol maintains a constant running speed with increase in grade 2. Interestingly, this shows that the individual characteristics of similar protocols do not impact VO2max but show inconsistencies in plateau. Their finding was one of the first to demonstrate the impact of protocol design characteristics on the attainment of VO2max and a VO2 plateau.
Early investigations by Whipp et al. It was proposed that ramp cycle protocols would improve an individual's ability to reach VO2max because the ramp increased work in a much more continuous fashion when compared to step increases in work rate used in traditional treadmill protocols [ 67 ].
In a similar study, Zhang et al.How to understand power - Eric Liu
Furthermore, this study emphasized the importance of work rate increments independent of the stage length used. In contrast, Myers et al. It was concluded that VO2, VCO2, respiratory exchange ratio RERHR, O2 pulse, ventilation, and respiratory muscle effort diaphragm responses were greater at maximal and submaximal workloads for treadmill compared to cycle exercise; however, the responses in ventilatory equivalents and ventilatory thresholds were similar.
Their results suggested that either mode may be applied for purposes of evaluating mode-specific fitness and determining optimal training prescriptions when work rate increases are applied in a ramp fashion. Similar to protocol mode cycle versus treadmillstage length, and work rate increments ramp versus stepGXT protocol duration should be considered when comparing results. Since VO2max values were greater in protocols lasting between 8 and 17 min compared to tests outside these limits, the current duration recommendation of 8—12 min was established [ 67 ].
More recently, Yoon et al. They found that VO2max was higher in men for the 8-minute protocol compared to 5-,and minute protocols, while there was no difference in VO2max in women.
This could be due to increased reliance on nonmitochondrial energy systems, thus causing premature fatigue, as well as eliciting central cardiovascular limitations. VO2max Protocol Paradigm Shift For the past 60 years the push to standardize GXT procedures has been essential to progress understanding of the complex and sensitive interaction between exercise and the integrated human physiological responses.
In spite of the advancements that have given test administrators the ability to control fixed increments of intensities in an open-loop fashion constant administrator testing variable manipulation without a fixed termination timerecent research has introduced an alternative approach to exercise protocols that allow the subject to self-pace the protocol in an incremental format [ 73 — 75 ].
In effect, this type of protocol would not negate past research that emphasized the role of the heart, lungs, circulatory, and other integrated systems in a limiting capacity but rather challenge the role of the brain as a potential simultaneous regulator. Although not entirely self-paced, studies by Pollock et al. In an effort to appreciate the evolution of self-paced protocols, the Pollock et al.
Hagerman [ 77 ] was the first to report the ability of an individual to reach a greater VO2 by self-pacing during a simulated competitive time trial compared to laboratory-based testing methods. The finding suggested that an individual's ability to self-regulate muscular power output may serve as the ultimate variable in maximizing physiologic responses. Intrigued by this finding, Foster et al. These initial findings raised an important fundamental question regarding exercise testing protocols: Similar RPE protocols using various stage lengths 2, 3, and 4 min have been validated to accurately predict VO2max [ 7480 — 83 ].
Using a similar perceptually regulated paradigm, Mauger and Sculthorpe [ 75 ] investigated a self-paced cycle exercise protocol in 16 untrained university students.
The protocol was designed as follows: It is important to note that the results of Mauger and Sculthorpe [ 75 ] have received considerable criticism over methodology. Moreover, the results support the role of the brain during a closed-loop setting when the individual is able to vary work rate constantly, balancing discomfort with a maintainable power output and willingness to complete the test.
The simplicity of the protocol design has produced many speculative explanations for the results. This study also received criticisms over flawed methods and lack of control, attributing findings to using different modes motorized versus nonmotorized treadmill and neglect of measurement error to test their hypothesis [ 8387 — 89 ].
Follow-up studies have shown a higher VO2max attainment during self-pacing using a cycle ramp protocol [ 90 ], similar VO2max attainment using motorized treadmill [ 8391 — 93 ] and cycle protocols [ 8494 ], and a lower VO2max attainment using an automated treadmill [ 89 ].
Critical Power: An Important Fatigue Threshold in Exercise Physiology
It is important to note that findings showing no difference between self-paced and traditional protocols demonstrate the potential utility for self-paced GXT protocols, particularly when considering protocol duration. While test duration is tightly controlled during self-paced testing and the incremental steps in oxygen cost between stages have been shown to fall within recommended guidelines METS [ 95 ], physiological measurements that may distinguish self-paced from traditional protocols have yet to be adequately examined.
It is purported that underlying variables that comprise the Fick equation, namely, Q and a-vO2diff, and the role of blood flow redistribution may underpin differences between self-paced and traditional protocols [ 9293 ]. More recently, Astorino et al. Additionally, they were the first to compare central cardiovascular responses between protocols and showed a higher Qmax during self-paced compared to ramp It should be noted that their average test duration was not tightly controlled to 10 min 9.
Although initial results are intriguing, the investigation into the efficacy and suitability of self-paced protocols is in its infancy. Therefore, future researchers could choose to design studies to expound on the intertrial reliability using self-pacing protocols. Additionally, studies should examine the interaction between central, peripheral, and central regulating responses during self-paced exercise.
VO2max Attainment Criteria In order to increase the reliability and validity of a test, an undefined combination of standardized criteria must be met during the GXT including the following: This widely accepted set of characteristics, or VO2max criteria, has become a controversial topic of debate in recent years due to the high intersubject variability in attaining the criteria [ 96 — 99 ].
Furthermore, the number and type of criteria used to determine VO2max are often contingent on the preference of the researcher or clinician administering the test [ 96 ].
Along with protocol design, other factors such as metabolic data processing methods and participant effort make comparing the results for clinical or research purposes difficult [ 5399]. Among the most important factors impacting the incidence of a VO2 plateau are age [ ], testing modality [ ], and data analyses methodology [ 99]. The diminished plateau in cycling was attributed to the increased metabolic cost of the eccentric skeletal muscle activity in treadmill running compared to the concentrically dominant cycle exercise.
Furthermore, Astorino [ ] confirmed that gas sampling rate impacted the incidence of a plateau. In this study, 13 sedentary, 48 recreationally active, and 47 competitive athletes completed a GXT using treadmill and cycle protocols. Collectively, these findings suggest that sampling rate in conjunction with the plateau threshold criteria may explain much of the discrepancy in incidence of VO2 plateau across studies.
Heart Rate Response to the VO2max Protocol Due to its noninvasive nature, simplicity, and fairly predictable response to incremental to maximal exercise, HR is often used as a secondary criterion to VO2 plateau. Much like plateau and other secondary criteria, the criteria for HR are highly variable.
Typically, the threshold is established at a specific percentage using an age-predicted HRmax equation. Surprisingly, Fox et al.
Robergs and Landwehr [ ] evaluated the Fox equation [ ] and highlighted the fact that there were no statistical methods used to establish the regression equation from their data set. The formula, age, defines a line not far from many data points.
It was concluded that the age equation underestimates age-predicted HRmax in individuals over the age of 40 years. Upon increasing metabolic acidosis, bicarbonate buffering leads to an increase in CO2 production, increased ventilation, and a subsequent increase in RER. A series of studies by Issekutz et al. The high intersubject variability in RER responses due to inconsistent effort levels and training status makes higher RER values difficult to achieve for many individuals [ 97 ].
While RPE is not a direct measurement of physiological responses, the behavioral, motivational, and physical factors that an individual perceives during GXT contribute greatly to the overall validity of the test. Many studies have shown a strong relationship between RPE, HR, and VO2 [ 82— ]; however, others have demonstrated RPE to be less related to these variables in less active or sedentary individuals . Due to the variability and subjective nature of the criterion, Magnan et al. Overall, the assumptions in employing an RPE criterion depend on the subject's understanding of the scale and associated verbal descriptors, ability to differentiate between discomfort and physiological fatigue, and motivation.
Verification Protocols of VO2max Many of the current criteria used to determine VO2max were established with technology that is no longer used today. Douglas bags and Tissot gasometers have been replaced by sophisticated metabolic analyzing systems and pneumotach and turbine flow measurement devices. Furthermore, the VO2max criteria were developed using certain modalities treadmill versus cycle on relatively small samples of homogenous populations.