Part 1
The equipment used to assess VO2 max and lactate threshold includes the h/p/cosmos Pulsar 5.0 treadmill, the Cosmed Quark PFT Ergo testing equipment, the Cosmed V2 mask, the HR Belt Cosmed-ANT (w/transmitter), and a computer.
Calibration Processes
The preliminary step for the experiment is to perform the calibration of the equipment. The treadmill velocity should be calibrated by marking a point and noting the time it takes to complete a predetermined number of revolutions. This time is used to calculate the velocity by using the length of the belt, which should also be measured. These calibrations should be performed at different speeds. The Cosmed Quark PFT should also be calibrated using the software which is self-explanatory and the user can complete the calibration process easily.
Significance of Calibration
The treadmill might have errors due to the mechanical motion. It is important to calibrate the treadmill to account for any errors that may be caused if calibration is not done. These errors must be accounted for in order to get accurate results.
Similarly, the PFT should also be calibrated in order to verify the accuracy of the results that it is transmitting and to account for any possible errors. These calibrations must be completed prior to starting the experiment to avoid any inaccuracies.
First of all, the height and weight of the test subject should be assessed. Specialized instruments should be used in order to do so. A portable or wall mounted stadiometer may be used to perform the height assessment, while a calibrated balance beam or electronic scale may be used to perform the assessment of weight (Parnell et al., 2011).
The subject should be instructed to wear suitable clothing such as cycling shorts, close fitting t-shirt, or sports bra appropriately. The skin areas should be prepared for the placement of markers (Jones et al., 2016).
The polar heart rate monitor should be worn according to the following instructions. The electrodes should be wetted before tying the strap around the chest tightly but comfortably. The contact of the wet electrodes with the skin should be ensured to allow a good heart rate signal (Polar, no date).
A proper sized VO2 mask should be selected for the subject that fits the face such that it covers the mouth and nose completely preventing any air leakage. The rest of the equipment should then be attached to the mask, such as the valve, the headgear and the hose. The mask should be adjusted using the Velcro straps (Korr Medical Technologies, 2016).
The baseline data should be recorded for determining the accuracy of measurement prior to performing the VO2 max and lactate threshold assessments.
The Protocols
Warm up protocols like static stretching, dynamic exercises, and dynamic stretching should be employed prior to performing the assessments. Static stretching includes 5 minutes of jogging and 7 minutes of stretching of the major muscle groups of the lower limbs. Dynamic exercises include exercises like speed skips, heel kicks, trunk twists, push-ups and other exercises. Dynamic stretching includes exercises like shoulder circles, arm swings, side bends, hip circles, leg swings, lunges and other exercises. However, (Rajpreet, Rajender and Jaspal, 2008) concluded that a statistically significant difference was observed in VO2 max using the three protocols and that dynamic exercises induced higher VO2 max values.
There are many methods that are employed for the assessment of lactate threshold. Three of them are discussed by Goodwin et al. (2007) which include the Visual Lactate Threshold method, the Dmax method, and the Onset of Blood Lactate Accumulation method. While numerous other methods are available for the assessment of lactate threshold, these three are known to be the best due to the description of the curvilinear profile. In the Visual LT method, two or more indicators are used to evaluate the graphical relationship between blood lactate and work rate to determine the threshold. The Dmax method employs a third order regression line of blood lactate versus work rate to determine the threshold point. Any of these methods may be used to determine the lactate threshold. Blood samples of 25 microliters may be collected from the earlobe and then analyzed for lactate concentrations.
The VO2 max should be assessed after the assessment of lactate threshold. Hogg, Hopker and Mauger (2015) provide the self-paced test for the determination of maximal oxygen uptake. A standard graded exercise test (GXT), an incline-based SPV, or a speed based SPV might be done to assess the VO2 max. The SPV protocol provides a more appropriate test for testing VO2 max in conditions such as the competitive sport of running. The SPV protocols include a 5 x 2-minute stage and a plateau verification stage and allow self-pacing with fixed increments of exertion rating.
The criteria for the measurement of VO2 max is given by Howley, Bassett and Welch (no date). The criteria depend upon the population of the study. The recommended method is to use the plateau and other criteria for experimental studies in which VO2 max is the primary dependent variable. This should be employed as the standard methodology to define the value of VO2 max in both pre-treatment and post-treatment.
Part 2
Creation of 3D Space
The 3D space should be set up so that it accounts for the major components of the device including the imaging hardware, a mounting system, a computer and the testing equipment. Ambient lighting requirements should be fulfilled to ensure adequate capture from the camera. Too bright or dark lighting may hinder in proper camera recording.
The 3D motion analysis system consists of body sensors, video capturing, and computer software. The software generates a 3D digital animation which allows the understanding of the different aspects of motion of the subject. Optimal camera exposure settings are essential to the accuracy of 3D marker tracking.
The camera exposure settings should be according to the cameras that are placed around the subject. The space in which the subject is present is known as the measurement volume characterized by the placement of markers around the subject.
Sampling should be done with the subject by placing the markers on the subject and allowing the subject to sit on the chair and adjust the cameras appropriately. The interpolation settings are available from the calibration settings of the equipment.
The three-dimensional motion analysis is done by placing markers on anatomical landmarks through which the software generates a representation of the subject’s movements. Four reflective markers may be used for the motion analysis system.
The calibration procedure involves placing the L-frame on the floor in the center of the capture volume and ensuring that each camera is viewing only the four markers on the L-frame. Cameras should be calibrated using the system. The preferable marker set is the non-traditional one because of the advantages it offers over the traditional non-CAST model.
There are a number of calibration methods available, however, the wand methodology is the most well-known one. The wand method employs a wand with an L-frame. The wand is waved in the 3D capture volume which is captured by the 3D motion analyzer system. The system generates a 2D arrangement of pictures which is then converted into a 3D animation. This is achieved by the help of the computer software, which is the key fragment of the motion analysis system.
The experimental procedure involves the assessment of mechanical energy of the endurance runners based on the VO2 max eligibility criteria. The mechanical energy assessment test employs the 3D motion analysis. The points on which the reflective markers are placed are spread all over the body. A number of recordings are made using the 3D motion analysis system to analyze the mechanical energy expenditure by the subject in a predetermined number of trials. The trials include a 1500 meters run. The recordings are then analyzed using the computer software.
The segmental method works by dividing the body into a number of segments and summing up the energy of separate segments and obtaining total body mechanical energy. The kinematic data is acquired by placing the markers on the anatomical landmarks in order to delineate the segment geometry and the location of the segment in the capture volume. The velocity, rotation and joint angle of each segment is calculated by filming the motion with the cameras that capture the movement of the markers. The segmental mechanical energy is calculated by calculating the potential energy due to gravity and the kinetic energy due to rotation and translation. This method is useful for the assumption of a rigid body; however, elastic potential energy is used to model the elasticity of the body parts. This elastic potential energy is too small to affect the overall segment energy and can be safely neglected. It is also possible to assume symmetry in the left and right limbs of the subject and measure only for one of the limbs and compound it for two limbs. The segmental method is preferable to the point mass method because it accounts for the limitations of the point mass method. These limitations include the negligence of the method of various aspects of the human movement such as the rotational kinetic energy and segmental motions. The result is that the point mass method ends up underestimating the overall mechanical energy expenditure of the subject and this is why the segmental method is favorable over the point mass method (Post, 2010).
Recent studies suggest that the mechanical intervention employs a 10-week running program for runners. It is also suggested that a Balke-Ware graded walking exercise test is conducted in combination with the bilateral kinetic and three-dimensional kinetic analysis before and after the running program. This mechanical intervention is believed to induce significant difference in kinematic and kinetic variables and the running economy in terms of the mechanical energy expenditure (Moore, Jones and Dixon, 2012).
References
Goodwin, M. L., Harris, J. E., Hernández, A. and Gladden, L. B. (2007) ‘Blood lactate measurements and analysis during exercise: a guide for clinicians.’, Journal of diabetes science and technology. Diabetes Technology Society, 1(4), pp. 558–69. Available at: http://www.ncbi.nlm.nih.gov/pubmed/19885119 (Accessed: 9 January 2017).
Hogg, J. S., Hopker, J. G. and Mauger, A. R. (2015) ‘The Self-Paced VO 2max Test to Assess Maximal Oxygen Uptake in Highly Trained Runners’, International Journal of Sports Physiology and Performance, 10(2), pp. 172–177. doi: 10.1123/ijspp.2014-0041.
Howley, E. T., Bassett, D. R. J. and Welch, H. G. (no date) ‘Criteria for maximal oxygen uptake: review and commentary’, Official Journal of the American College of Sports Medicine, pp. 1292–1301.
Jones, G. D., James, D. C., Thacker, M. A. and Green, D. A. (2016) ‘Sit-to-stand-and-walk from 120% knee height: A novel approach to assess dynamic postural control independent of lead-limb.’, Journal of Visualized Experiments, In Press(August), pp. 1–17. doi: 10.3791/54323.
Korr Medical Technologies (2016) Fitting a VO2 Mask - CardioCoach Training, Youtube. Available at: https://www.youtube.com/watch?v=bB_D8AwdJSY (Accessed: 9 January 2017).
Moore, I. S., Jones, A. M. and Dixon, S. J. (2012) ‘Mechanisms for Improved Running Economy in Beginner Runners’, Med. Sci. Sports Exerc, 44(9), pp. 1756–1763. doi: 10.1249/MSS.0b013e318255a727.
Parnell, S., Streur, W. J., Hurlburt, W. B. and Birch, S. (2011) ‘Measuring Height/Weight and Calculating BMI Guidelines for Schools’.
Polar (no date) How to wear a heart rate sensor with textile strap, support.polar.com. Available at: http://support.polar.com/en/support/tips/How_to_wear_a_heart_rate_sensor_with_textile_strap (Accessed: 9 January 2017).
Post, A. (2010) ‘Energy, thermodynamics, and work: Energy flows and its application in human movement analysis’. Available at: https://www.researchgate.net/profile/Andrew_Post/publication/236857611_Energy_thermodynamics_and_work_Energy_flows_and_its_application_in_human_movement_analysis/links/02e7e5199178cc3942000000.pdf (Accessed: 9 January 2017).
Rajpreet, K., Rajender, K. and Jaspal, S. (2008) ‘Effects Of Various Warm Up Protocols On Endurance And Blood Lactate Concentration’, Serbian Journal of Sports Sciences, (4). Available at: http://sjss-sportsacademy.edu.rs/archive/details/general/effects-of-various-warm-up-protocols-on-endurance-and-blood-lactate-concentration-34.html (Accessed: 9 January 2017).
