Near Infrared Spectroscopy is not a Surrogate of Venous Occlusion Plethysmography to Assess Microvascular Resting Blood Flow and Function

International Journal of Exercise Science 15(2): 1616-1626, 2022. Near-infrared spectroscopy (NIRS) is a non-invasive technique that measures tissue perfusion using red blood cells oxygen saturation and venous occlusion plethysmography (VOP) is the gold standard to assess microvascular blood flow and function. The purpose of this study was to determine if NIRS can surrogate the microvascular blood flow assessment after an ischemic challenge obtained via VOP. Twenty apparently healthy subjects (10 males and 10 females), aged 18 to 35 years, were recruited for this single session study. NIRS probes were placed 40mm apart along the epicondylar muscles on the right forearm and on the tibialis anterior on the right lower leg, while VOP strain gauges were placed on the largest circumference on both right forearm and calf. Blood flow via VOP and NIRS variables (hemoglobin saturation (SO2), oxygenated hemoglobin (HbO2), and deoxyhemoglobin (HHb) slopes) were assessed before and after 5-min ischemic challenge. Person’s correlations and intra-class correlations (ICC2k) were conducted for each of the NIRS variables vs VOP. There were moderate associations between of SO2 and HbO2 slopes and VOP (r = 0.59, p \u3c 0.01 and r = 0.53, p \u3c 0.05, respectively) at the lower body during resting conditions. There was a poor agreement between NIRS SO2 and VOP at the resting condition in the lower body (ICC2k = 0.45). There were no other associations between any of the other NIRS variables and VOP of the lower and upper body at resting or post-ischemic conditions. In conclusion, NIRS cannot surrogate VOP for measurements of microvascular blood flow at resting or post-ischemic conditions

The Effects of Two Different Sprint Training Modalities on Sprint Speed, Aerobic Fitness and Body Composition

Previous studies on sprint training have shown subjects to improve not only sprint speed, but also aerobic fitness and body composition. However, it is unclear whether sprint training on the track is more effective in improving these variables compared to training on a high-speed treadmill. The purpose of this study was to examine the effects of a 6-week track (TR) vs. high-speed treadmill (TM) sprint training on maximal aerobic capacity (VO2max), sprint speed and body composition. Twelve subjects were randomly assigned to the TR (n=6; 3 males, 3 females) or TM training group (n=6; 3 males, 3 females). All subjects performed 2 training sessions weekly, performing 4 maximal sprints with 3-4 minutes rest in between attempts. Four cones were placed along the track to simulate progression of speed to replicate treadmill conditions. TR started from an upright jog position and progressively increased speed at each cone (60%, 70%, 80%, and 90%) of maximal speed and 100% maximal speed through the recording zone (5-6 seconds). A treadmill speed test was applied increasing treadmill speed to the subjects’ loss of control, while suspended in a safety harness. VO2max was measured by Parvomedics True Max 2400 metabolic cart and body composition was measured by Dual Energy X-ray absorptiometry (DXA) at baseline and after the 6 weeks of training. Treadmill sprint speed improved significantly in both groups (TR 16.36±0.54 to 17.79±0.52 miles/hr, p=0.0003; TM 17.13±0.84 to 18.63±0.93 miles/hr, p=0.0018). VO2 max was improved in both groups (TR 46.60±2.03 to 49.54±1.71 ml/kg/min, p=0.03; TM 47.59±4.152 to 51.05±4.445 ml/kg/min, p=0.04). There was no significant change in body mass index (TR 24.1±1.0 to 24.0±1.0 kg/m2; p=0.51; TM 24.5±0.7 to 24.1±0.8; p=0.30) or in lean mass (TR 44.08±3.12 to 43.80±2.62 kg; p=0.73; TM 48.41±5.29 to 44.55±7.49 kg; p=0.36) in either group. There was a significant decrease in percent body fat in the TR group (30.36±3.75 to 29.20±3.75%; p=0.01) but not in the TM group (27.83±5.50 to 27.20±5.95%; p=0.38). In summary, both the track and treadmill sprint training modalities appear to be effective to improve sprint speed and aerobic power after only 6 weeks of training. However, only track sprint training appears to be beneficial towards decreasing body fat

Biomechanical Characteristics of the Carotid Artery during Aerobic Exercise

Cardiovascular disease is known as the leading cause of death, including coronary artery disease and stroke. Atherosclerosis is responsible for 9 in every 10 cases of stroke. The prevention of stroke and other cardiovascular diseases is possible through aerobic exercise (AE). However, not much is known about the biomechanical characteristics of the carotid artery during AE. PURPOSE: To estimate arterial stiffness in-vivo during submaximal cycling exercise at three different exercise intensities. METHODS: 20 apparently healthy young adults participated in two laboratory visits. First visit, subjects were laid down on a medical bed, in which resting pressure, maximal/minimal artery diameter, and blood flow velocity of the carotid artery were obtained. Three recordings were obtained with a coefficient of variation (CV) of less than 5%. Compliance and stiffness were calculated from the collected data. Thereafter, subjects performed a cardiopulmonary exercise test (CPET) with a graded exercise test protocol. In session two, participants performed for three submaximal intensities stages, three minutes per stage, in which the intensities were determined via lactate levels of initial CPET, low intensity: 4.0 mmol/L. Throughout each stage, the same data as resting conditions were obtained as well as blood flow patterns. RESULTS: There were no differences in any of the biomechanical characteristics between resting and any of the exercise intensities (p\u3e0.05). However, there was a significant interaction by participants (p\u3c0.05). CONCLUSION: Even though the estimation of arterial stiffness per condition was not significantly different, a larger sample size, due to a significant interaction by subject, might show a different result

A Comparison of Morphological, Jump, and Sprint Kinematic Asymmetries in Division I Track and Field Athletes

International Journal of Exercise Science 16(1): 1306-1319, 2023. Inter-limb asymmetries are the difference in performance in one limb with respect to the other. Running events in track and field are considered symmetrical while jumping and throwing events are considered asymmetrical. It is unknown if competing in these different events result in differences in inter-limb asymmetries, thus, this study compared the magnitude of jump, sprint, and morphological asymmetries in track and field athletes who compete in symmetrical and asymmetrical events. Forty-six Division I track and field athletes performed a series of vertical jumps (VJ) and broad jumps (BJ) with force platforms measuring peak force of each limb, and 30-meter fly sprints with kinematics (step length (SL), flight time (FT), and contact time (CT)) recorded during the sprints. Additionally, thirty-eight of these subjects underwent body composition analysis via dual x-ray absorptiometry to determine morphological asymmetries. Asymmetries were calculated using the symmetry index and the asymmetry measures were compared between sprinters, distance runners, throwers, and jumpers utilizing a one-way analysis of variance or Kruskal-Wallis tests with post-hoc comparisons as necessary. There were no differences in VJ, BJ, and sprint kinematic asymmetries found between groups but there were differences in leg fat mass asymmetries (H(3)=8.259, p=0.041, eta2= 0.101) as well as arm lean mass (H(3)=9.404, p=0.024, eta2=0.152), fat mass (H(3)=17.822,

Validity of Vertical Jump Measuring Devices

The vertical jump has been used to assess athleticism in explosive sports. Field measuring methods have been recently introduced to the market. Some of these devices have been previously validated, however, they have not been validated by an independent research institute nor have been concurrently validated in the same training session. PURPOSE: This research intends to conduct an independent validation of alternative vertical jump devices and to validate multiple devices within the same training session. METHODS: 50 physically active University students were recruited for this study. The subjects performed a self-paced 5 minute jog on a treadmill as part of the general warm-up followed by an 8 minute specific dynamic warm up. Subjects then performed a familiarization phase on the force plates, which consisted of 3 repetitions of the countermovement jump (CMJ); in order to control for individual technical differences and intra-subject variability, subjects were instructed to perform a CMJ at a 90 degree angle squat for each repetition. Subjects then performed a CMJ at the researchers signal for 3 repetitions. We placed an accelerometer based device (Push-Band) on the subjects waist, an Iphone 7plus was used to record and analyze the subject’s CMJ on two video apps (MyJump2 and What’sMyVert), and a photoelectric cells system (optojump) bars were placed next to the force plates; the later were used as the gold standard for the vertical jump measure. 3 researchers measured synchronically each CMJ. A data analysis was conducted on IBM SPSS 23. An Intra-class correlation was used to analyze the correlation between devices. RESULTS: Compared to the force plates, the MyJump2 app showed a nearly perfect correlation (r=.968). The Whats’myVert video app and PushBand showed a moderate-large correlation (r=.619 and r=.641 respectively). Lastly, the Optojump showed a moderate correlation of r= .492. CONCLUSION: We observed a nearly perfect correlation of the MyJump2 app, this correlation appears to be consistent to a previous validation study. The What’sMyVert app showed a large correlation to the force plates, and to our knowledge, this is the first study looking at the validation of this app. We found some inconsistency between our data from the PushBand accelerometer and the Optojump to what has been previously published. In summary, based on our data, the video apps appear to be an excellent alternative to costly laboratory and field devices

The Effects of Different Intensities on Eccentric Cycling Blood Flow Patterns at a Concentric Cycling Workload Match

Decrease of blood flow to tissues, due to plaque built by atherosclerosis, increases mortality and morbidity. Homeostatic balance in the vascular system depends directly on endothelial cells, and blood flow, better known as endothelial sheer stress (ESS). Different types of blood flow patterns have been established measured by Reynolds number (Re), and turbulent flow has been associated with the decrease of ESS. Eccentric exercise (ECC) has gained attention as a novel exercise modality that increases muscle performance without increasing metabolic demands; however, little is known about ESS during ECC. PURPOSE: To determine the effects of ECC cycling in blood flow patterns in young, apparently healthy individuals. METHODS: 18 apparently healthy participants, were recruited for two laboratory visits. First visit served to obtain maximum oxygen consumption and peak power (PP), to determine workload intensities, followed by a 5-min familiarization on eccentric ergometer. Second visit on eccentric ergometer assessed blood flow patterns (i.e. ESS and Re measured via imaging ultrasound and Doppler) during a 3-workload steady exercise test at low, moderate, and high intensities. RESULTS: There was an interaction of exercise intensity on antegrade ESS (F(3,53.7)=26.90, p\u3c0.001), but not Sex (p\u3e0.05), and a random effect of participant (p\u3c0.001) and Re anterograde (F(3,53.6)=25.03, p\u3c0.001), but not Sex or random effect of participant (p\u3e0.05). There was an interaction of condition on retrograde ESS (F(3,53.4)=11.21, p\u3c0.001), but not Sex (p\u3e0.05), and a random effect of participant (p\u3c0.001). and Re retrograde (F(3,54.3)=12.34, p\u3c0.001), Sex (F(1,18.5)=4.41, p=0.05), and random effect of participant (p\u3e0.05). CONCLUSION: Eccentric cycling exercise produces exercise-induced blood flow patterns that are intensity-dependent in males and females and these patterns are similar to traditional concentric cycling

Associations Between Jump Performance and Asymmetries with 30-m Sprint Completion Time

Asymmetries of the lower body during jumping have been examined as a method to predict risk for injury and guide training program development. Studies have primarily focused on how these asymmetries affect jump performance, but none have examined this in Division I track athletes nor how these are related to sprint performance. PURPOSE: To examine the relationship between jump performance and asymmetries of the vertical and broad jumps with 30-m sprint completion times. METHODS: Twenty-five Division I Track and Field athletes (12 sprinters and 13 non-sprinters) (height = 177.21 ± 10.43 cm; weight = 78.67 ± 24.15 kg) participated in this study. These subjects performed two trials of both the vertical jump (VJ) with their hands on their hips while standing on force platforms. Subjects also performed two trials of the broad jump (BJ) while standing on force platforms and the distance of the BJ was measured using a 100-m tape measure. Following the jump tests, subjects performed two trials of 30-m sprints in which time was recorded using timing gates and the trial with the shortest completion time was used for analysis. Force data from the VJ was used to determine jump height and inter-limb asymmetries and the trial with the greatest jump height was used for analysis. Force data from the BJ was used to determine inter-limb asymmetries from each trial and the trial with the greatest jump distance was used for analysis. Asymmetries were calculated with the symmetry index equation [(high value-low value)/total*100]. Spearman rank correlations were then conducted to determine if the jump performance and asymmetries were associated with sprint completion times. Significance was set at an alpha level of 0.05. RESULTS: Spearman rank correlations determined that both the VJ and BJ were negatively associated with 30-m sprint completion time (rs= -0.644 p=0.001 and rs=-0.563 p=0.003, respectively). Additionally, both the VJ height and BJ distance were positively correlated (rs=0.643 p=0.001). The VJ and BJ asymmetries were not significantly correlated with 30-m sprint performance (p\u3e0.05) nor were they correlated with either the VJ height or BJ distance. CONCLUSION: The findings of study indicate that coaches may want to monitor jump performance as it is related to sprint performance. On the other hand, the asymmetries measured were not associated with jump or sprint performance and this may be due to the sample as they were highly trained individuals with low levels of asymmetries during both jumps

Association Between Single-Leg Agility and Single-Leg Vertical Jumping Performance in Active Adults

The vertical jump is crucial in sports and indicates lower body explosiveness. Additionally, vertical jumping requires landing bilaterally or unilaterally. PURPOSE: To determine any differences in unilateral vertical jump performance when landing unilaterally or bilaterally. METHODS: Thirty recreationally trained individuals (age = 23.5 ± 2.2 years) performed three trials of vertical jumps under four different conditions in random order (unilateral-left vertical jump with bilateral landing, unilateral-right vertical jump with bilateral landing, unilateral-left vertical jump with ipsilateral landing, and unilateral-right vertical jump with ipsilateral landing). Kinetic data (peak force, relative peak force, peak power, and relative peak power) was obtained from all jumps at 1000 Hz sampling rate. The average score between trials for the vertical jump were used for statistical analysis in SPSS 25. Independent T-tests were used to find differences in vertical jump measures depending on landing condition with p-value at 0.05. RESULTS: No significant differences between limbs in jump height (Right = 0.08 cm ± 0.04; Left cm = 0.11 ± 0.05), peak force (Right = 473.3 N ± 135.6; Left = 600.1 N ± 182.6), relative peak force (Right = 6.8 N*kg ± 2.6; Left = 7.8 N*kg ± 1.9), peak power (Right = 1505.4 W ± 524.5; Left = 1934.9 W ± 771.9), and relative peak power (Right = 21.3 W*kg ± 7.2; Left = 25.5 W*kg ± 5.8) during unilateral vertical jumps between the landing conditions (p \u3e 0.05). CONCLUSION: It appears that landing conditions do not affect unilateral jump performance in recreationally trained athletes

The Relationship between Squat Jump Performance and Sprint Profile in Collegiate Track and Field Athletes

The squat jump (SJ) necessitates the inter-play of various biomechanical components for better jump performance. Good sprint performance requires the inter-play of many of the same biomechanical components. Researchers have previously examined how the speed, force, velocity, and power interact during sprinting, but have yet to examine how these measures are associated with SJ performance measures. PURPOSE: Examine the relationship between squat jump performance measures and the sprint profile measurements of collegiate track and field athletes. METHODS: Twenty-five athletes (18 males and 7 females) completed two squat jump trials with a linear encoder attached to a 45 lbs. bar placed on the athlete’s upper back. Measures of interest during the concentric phase of the SJ included jump height, maximum force, maximum velocity, maximum power, and rate of force development. Athletes then completed two 30-meter acceleration sprints. The MySprint mobile application was used to acquire the athlete’s sprint profile and to assess maximal theoretical horizontal force, maximal theoretical velocity, optimal velocity, maximal theoretical power, maximal speed, maximal ratio of force, force-velocity slope, and decrease in ratio of force. The best trial was used for statistical analysis. Pearson’s or Spearman’s correlation coefficients were conducted between SJ measures and sprint profile measures. RESULTS: There was a positive correlation between SJ height and maximal speed (r = 0.402; p = 0.042). Maximal power during the SJ was positively correlated with maximal speed (r = 0.476; p = 0.014); optimal velocity (r = 0.469; p = 0.018); maximal theoretical power (r = 0.462; p = 0.018); maximal theoretical velocity (r = 0.452; p = 0.021); theoretical horizontal force (r = 0.431; p = 0.028); and maximal ratio force (r = 0.428; p = 0.029). Maximal velocity during the SJ was correlated with maximal speed (r = 0.519; p = 0.007); maximal theoretical velocity (r = 0.499; p = 0.010); optimal velocity (r = 0.486; p = 0.014); and maximal theoretical power (r = 0.484; p = 0.012). No other correlations were significant. CONCLUSION: Maximal velocity and power during the concentric phase of the SJ are moderately to strongly correlated with maximal sprinting speed, velocity, and power. SJ height is positively correlated with maximum sprint speed. There is a lack of significant correlations between other measures of the SJ and sprint profile measures. SJ power and velocity are correlated with sprint performance, therefore power and velocity improved through plyometric SJ training may be transferable to achieve better sprint performance