The Influence of Bicycle Geometry on Time-Trial Positioning Kinematics and Markers of Performance

Studies have previously documented how changes in cycling body kinematics are related to submaximal energetics and power output, as well as cycling performance, but few have focused specifically on how body kinematics will vary with changes in bicycle geometry. This study sought to describe kinematic changes resulting from the systematic change of several bicycle geometry variables: Trunk angle (“low” and “high” positions), seat-tube angle (76° and 80°), saddle tilt angle (0° to -10°), saddle sitting position (middle or nose), as well as two types of saddles. Methods: Well-trained cyclists were kinematically evaluated across specific combinations of geometry variables using a modified cycle ergometer at a standard relative power. Standard two dimensional sagittal-view kinematics from the left side were used to summarize a collection of kinematic variables: Trunk angle, hip angle (HA), knee angle, pelvic tilt angle, and two “composite” angles called body position and pelvic position (PP). Finally, each trial was also evaluated for frontal area (FA; m2) from stationary digital photography. Data were evaluated using repeated measures ANOVA (a=0.05) to evaluate change in kinematics between trials, as well as regression analysis to determine predictability of performance markers (HA and FA) from the collection of geometry and kinematic variables. Results: Changing trunk angle had the greatest impact on other kinematic variables, while saddle type had no influence. Regression showed that geometry variables could explain 75-85% of the variability in either HA or FA, while 78-79% of the variation in HA and 83- 84% of FA was explained by PP alone. Conclusions: The composite kinematic measure PP was generally a better predictor of both HA and FA than any combination of geometry variables. These results can serve as a starting point for understanding the interactions between bicycle geometry and body kinematics, both of which are important determinants of power generation and aerodynamic drag

Characterizing the Metabolic Intensity and Cardiovascular Demands of Walking Football in Southeast Asian Women

Given that the recent rise in obesity rates throughout Southeast Asia is disproportionately driven by women, part of the regional solution may be to encourage more habitual physical activity within this population. Taking advantage of the regional popularity of walking football, this study sought to characterize the cardiovascular demands and metabolic intensity of Southeast Asian women competing in walking football matches to determine the sports’ suitability for promoting physical health. It was hypothesized that both cardiovascular and metabolic intensity measures (≥65% HR% and ≥3.0 METs, respectively) would meet or exceed established thresholds for improving fitness and health. Methods: Women’s teams from Singapore (Mean±SD: 42±11 yrs age; 29.2±7.0 kg/m2 BMI; n=14) and Malaysia (40±10 yrs age; 32.9±5.7 kg/m2 BMI; n=8) competed in two successive matches within a single day during which measures of heart rate (HR) and GPS (from portable handheld device) were recorded for each player, while relative HR was computed as a percent of each player’s age-predicted maximal HR (HR%, %). The GPS data were later converted to walking distance and metabolic intensity (i.e., metabolic equivalents, or METs). One-sample t-tests at the 0.05 alpha level were used to compare variables to their respective thresholds. Results: Both Malaysian and Singaporean teams had mean relative HRs (91-95% of HRMAX [P=0.008] versus 77-80% of HRMAX [P<0.001], respectively) that exceeded the 65% threshold for improving cardiovascular fitness. Both teams also maintained an average metabolic intensity that was statistically similar to the 3.0 MET threshold that decreases one risk for non-communicable diseases (3.2±0.9 METs [P=0.0510] versus (3.3±1.0 METs [P=0.288], respectively), and both teams walked an average of 2.2-2.4 kms/match. Conclusions: These results support the idea that competitive walking football is of sufficient intensity to promote positive changes in both cardiovascular and metabolic fitness in this population of Southeast Asian women

INFLUENCE OF WEARING A BELT-SUPPORTED ARMORED VEST ON THE ENERGETICS OF OVERGROUND LOCOMOTION

L.M. Whalen1, K.A. Pribanic2, & D.P. Heil1 1Movement Science/Human Performance Laboratory, Montana State University, Bozeman, MT 2Mystery Ranch LTD, Bozeman, MT Standard loads carried by military ground troops on patrol can include a rifle, an operations kit, a loaded backpack, and an armored vest, such as the modular tactical vest (MTV) used in this study. As load mass increases, so does the potential for fatigue and injuries. Finding the most economical load carriage system may allow troops to perform their duties in the safest and most effective manner. PURPOSE: This study assessed the energetic and kinematic effects of supporting an MTV with a backpack-style hip belt during overground hiking. It was hypothesized that the energetics of overground hiking with an MTV would improve with the use of a hip belt. METHODS: Nine women and eight men (Mean±SD: 25±8 years) hiked a 586 m unpaved, outdoor path, carrying a dummy rifle, under three conditions: wearing no MTV (Control); wearing a 17.7 kg MTV (A condition); wearing an MTV with an attached 0.6 kg hip belt (AB condition). Subjects hiked under each condition at three speeds: 67.0 m/min; 80.4 m/min; 93.8 m/min, for a total of 9 trials. Data for stride rate (SR; steps/min), energy expenditure (oxygen uptake, VO2; ml/min), and heart rate (HR; BPM) were measured with accelerometers and a portable metabolic system, then summarized for each trial and analyzed using a multivariate repeated measures ANOVA and Sheffe’s post-hoc at the 0.05 alpha level. RESULTS: At all speeds, SR was always lowest for the Control condition and highest for the AB condition, though not significantly (P\u3e0.05). VO2 and HR were higher for the AB condition than for the Control and A conditions at all speeds, though not significantly (P\u3e0.05). CONCLUSION: The use of an MTV with a hip belt was unexpectedly associated with non-significant trends to increase VO2, HR and SR for all hiking speeds. While many subjects noted greater shoulder comfort when using the hip belt, it is speculated that the belt’s repositioning of the MTV mass necessitated greater balance control during overground hiking, which then caused the observed increases in VO2 and SR. Further research should focus on a similar measurement strategy with attention paid to the mass distribution on the MTV as well as the fit of the MTV with reference to gender and body size of the wearer. Study funded by Mystery Ranch LTD (Bozeman, MT

TEST-RETEST RELIABILITY OF BLOOD LIPID MEASUREMENTS USING A DESKTOP LIPID ANALYZER

TEST-RETEST RELIABILITY OF BLOOD LIPID MEASUREMENTS USING A DESKTOP LIPID ANALYZER C.W. Kirven, L.M. Whalen, and D.P. Heil FACSM Movement Science / Human Performance Lab, Department of Health and Human Development, Montana State University, Bozeman, MT, Blood lipid measurements are an important factor in determining an individual’s risk for cardiovascular disease. Accurately measuring and monitoring blood lipids plays a critical role in the management of an individual’s blood lipids. However, the accuracy of blood lipid measurements is dependent upon the validity and reliability of the equipment used. PURPOSE: This study investigated the test-retest reliability of blood lipid measurements using a desktop lipid analyzer. METHODS: Four women and six men donated two fingertip blood samples during a single laboratory visit. High-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides (TRG) levels were measured in duplicate from two separate fingertip whole blood samples. Test-retest reliability for the HDL, LDL, and TRG measures were assessed using 2-Factor repeated measures ANOVA, the intraclass correlation coefficient (Rxx; stability reliability), and the standard error of measurement (SEM). Values for Rxx and SEM were computed for all two samples (k=2), as well as extrapolated for one sample (k=1). For the purpose of this study, an Rxx value greater than 0.80 was considered to be an acceptable level of reliability. RESULTS: Mean values for HDL and LDL across the two measurements were statistically similar (P=0.47, P=0.24 for HDL and LDL respectively). However, mean values for TRG between two trials were statistically different (P=0.011). Rxx (k=2) across two measures of HDL was high (0.96) with a relatively low SEM value (±3 mg/dL). When extrapolated to a single measure (k=1), Rxx was also high for HDL (0.92) with a relatively low SEM (±4 mg/dL). Rxx (k=2) across two measures of LDL was high (0.91) with a moderate SEM value (±8 mg/dL). When extrapolated to a single measure (k=1), Rxx was lower for LDL (0.83) with a moderate SEM (±11 mg/dL). Rxx (k=2) across two measures of TRG was high (0.96) with a moderate SEM value (±10 mg/dL). When extrapolated to a single measure (k=1), Rxx was high for TRG (0.93) with a moderate SEM (±13 mg/dL). CONCLUSIONS: All three measures, HDL, LDL, and TRG showed strong evidence of intraclass reliability, with HDL showing the strongest evidence of reliability and TRG showing the weakest evidence of reliability. Consequently, a desktop lipid analyzer is a reliable instrument when using a single finger prick blood sample for measuring HDL, LDL, and TRG. Supported by a grant from Meehan Formulations, LLC (Jackson, WY

HEART RATE RESPONSES PRIOR TO AND DURING A 15-KM SKATE SKI RACE: A PILOT STUDY

E.C. Ranta, T. Vetrone, & D.P. Heil Montana State University, Bozeman, MT The unique population of Masters-level cross country ski racers has been largely overlooked in prior ski research. In order to accurately develop coaching techniques for Masters skiers, current training practices and race strategies must first be understood. Collecting heart rate (HR) response data, through the use of telemetry-based heart rate monitor (HRM) systems, is one method of characterizing these athletes. PURPOSE: This study tested the feasibility of utilizing HRMs as a means to collect HR data on multiple Masters-level cross country ski racers competing simultaneously. A secondary purpose was to explore correlations between warm-up (WU) and race HR responses. METHODS: Five men and two women volunteered to participate in the study. Two subjects were dropped from the results due to incomplete data collection and imprecise HRM recordings. The remaining four men (M±SD: 43±7 yrs; 71.8±5.3 kg; 179.1±2.5 cm; 8±4.3 yrs race experience) and one woman (38 yrs; 67.1 kg; 172.7 cm; 1 yr race experience) wore telemetry-based HRM systems (set at 5-sec sample intervals) during a 15-km skate ski race, in addition to the 45-min WU period immediately preceding the race. Subjects were instructed to warm-up and race as they would normally. Participants also filled out an online questionnaire for self-reporting of demographic, training, and racing history. HR data was downloaded to a computer and summarized for both the WU and race periods. Race HR was defined as two minutes past the initial onset of a steady-state HR through the last highest recorded HR value. Summary HR values were then combined with race performance times and compared using Pearson’s correlation at an alpha of 0.10. RESULTS: Average race and WU HR were 168±4 BPM and 124±16 BPM, respectively, while WU HR as a percentage of race HR was 74%±7%. Race time correlated significantly with WU time spent at or above average race HR (r =0 .971; P = 0.006), while average race HR correlated significantly with average WU HR (r = 0.948; P = 0.014) as well as WU time spent within the subject’s range of race HR (r =0 .930; P = 0.022). CONCLUSION: The use of telemetry-based HRM systems are a feasible option for characterizing the WU and race HR response patterns of Masters-level skiers despite the mass start format and extremely cold air temperatures (-22˚C). Additionally, WU HR patterns correlated well with self-selected race pacing strategies within this particular population. Although future studies would benefit from increasing subject recruitment and reducing HRM data collection errors, similar methodological strategies are practical for further examining the training and racing practices of Masters-level cross country skiers

DISTRIBUTION OF PRESEASON TRAINING INTENSITY IN MASTERS-AGED COMPETITIVE CROSS COUNTRY SKIERS

DISTRIBUTION OF PRESEASON TRAINING INTENSITY IN MASTERS-AGED COMPETITIVE CROSS COUNTRY SKIERS E.C. Ranta, T.K. Vetrone, and D.P. Heil, FACSM Montana State University, Bozeman, MT INTRODUCTION: The distribution of preseason training intensity amongst competitive Masters-aged cross country (XC) skiers has been largely overlooked in the research literature. To develop effective training programs for these athletes, current training practices must first be understood. Thus, the purpose of this study was to classify the weekly training practices of competitive Masters-aged XC skiers during the 2013 preseason (August-October) using telemetry-based heart rate monitors (HRM). METHODS: Fifty-seven competitive XC skiers, all 40+ years of age, volunteered to wear a HRM (5-sec recording interval) and use a training log to record all bouts of exercise over 14 consecutive days of typical preseason training. Subjects who donned the HRM for less than 70% of their logged training time were excluded from the study due to insufficient data collection. Heart rate data were downloaded to a computer and summarized by both absolute training time (T, mins) and relative time (P, %) spent within six HR zones (Z) calculated as a percentage of age-predicted maximum HR (APMHR): Z5= HR≥90% of APMHR; Z4= 80%55 yrs.) using two-sample T-tests (0.05 alpha). RESULTS: Only 41 of the 57 subjects recorded adequate data for evaluation. These 22 men (Mean±SD: 57±8 yrs.; 23.5±1.8 kg/m2) and 19 women (56±7 yrs.; 21.0±1.1 kg/m2) reported significantly less T in Z5 when compared to Z0-Z4 (Mean±SE: 35.9±5.3 vs. 76.0±12.6, 116.5±10.9, 136.6±8.0, 125.8±8.8, 88.6±8.5 mins/wk for Z0-Z4, respectively) as well as significantly less P within Z5 when compared to Z1-Z4 (6.8±1.1% vs. 19.5±1.3%, 23.5±1.0%, 22.2±1.4%, 15.9±1.4% for Z1-Z4, respectively). Additionally, the male subjects recorded significantly (P\u3c.01) more exercise bouts per week on the training logs and HRM than the female subjects (10.4±.75 vs. 7.9±0.5 and 8.6±0.7 vs. 6.3±0.3 bouts/wk, M vs. F, respectively). There were no significant differences between age groups. CONCLUSION: The relatively even distribution of Z1-Z4 training time, with significantly less Z5 time, is contrary to the preseason polarized training regimen followed by elite athletes. For Masters skiers to achieve a more optimal training distribution, akin to competitive elite athletes, emphasis should be placed on increasing the P spent in Z1, Z2, and Z5 while simultaneously decreasing the P spent in Z3 and Z4

RELIABILITY OF OXYGEN CONSUMPTION AND HEART RATE AS FUNCTIONS OF POWER DEMAND WHILE ROLLER SKIING

T.J. Reinking, B.W. Reinking, & D.P. Heil Montana State University, Bozeman, MT A recent study investigated Nordic skiers’ anaerobic capacities by calculating the accumulated oxygen (VO2) deficit from a maximal roller ski test. The calculation of VO2 deficit required a submaximal graded exercise test (GXT) to assess the relationship between the calculated external power demand (PD) and the skier’s oxygen consumption (VO2). However, the reliability of the protocol used to establish this relationship has not been tested. PURPOSE: To investigate the test-retest reliability of using a roller ski GXT for determining the relationship between physiological markers (VO2 and heart rate) and external power demand. METHODS: Seven male collegiate Nordic ski racers (Mean±SD, Range: 21±1, 19-22 years; 181.5±10.5, 174-198.1 cm; 77.0±13.2, 61.2-100.5 kg) completed two roller skiing GXTs on two separate days with 24-96 hours between trials. Subject heart rate (HR) and VO2 were measured continuously and averages from the last 2 minutes of each 4-minute stage were considered steady-state values. PD was calculated as the sum of rolling resistance from the roller ski wheels on the treadmill and gravitational resistance from treadmill grade. PD was then plotted against steady-state VO2 and HR values. Slope and intercept terms were generated for each variable as a function of the skier’s power output using standard linear regression. Reliability of the slope and intercept terms were evaluated using a two-factor, repeated-measures ANOVA (α=0.05), an intraclass correlation coefficient (ICC) and the standard error of measurement (SEM); the latter two of which were computed for both 2-trial and 1-trial reliability. RESULTS: There were no significant differences between trials for all variables (P=0.69-0.98). ICC values were moderate to high for both 2-trial (0.76-0.95) and 1-trial (0.62-0.91) assessments. Highest ICC values were from VO2 slope and HR slope. Similarly, the SEM was low for both 1-trial and 2-trial VO2 (±0.01 for both) and HR slopes (±0.03 and ±0.02, respectively). HR intercept showed moderate reliability (2-trial ICC=0.86, SEM=±5.06; 1-trial ICC=0.75, SEM=±6.69), and VO2 intercept was slightly less reliable (2-trial ICC=0.77, SEM=±1.75; 1-trial ICC=0.62, SEM=±2.23) CONCLUSIONS: The HR and VO2 slope parameters were both considered more reliable than the corresponding intercept parameters, though all variables showed moderate to high test-retest reliability. This analysis suggests that one roller ski GXT sufficiently approximates the VO2 and HR slope relationships

CHARACTERIZING PRE-SEASON TRAINING HABITS OF COMPETITIVE MASTERS-AGED CROSS-COUNTRY SKIERS

CHARACTERIZING PRE-SEASON TRAINING HABITS OF COMPETITIVE MASTERS-AGED CROSS-COUNTRY SKIERS T.K. Vetrone, E.C. Ranta, & D.P. Heil, FACSM. Movement Science \ Human Performance Lab, Montana State University, Bozeman, MT Introduction: The training habits of Masters-aged cross-country skiers (i.e., those 40+ years of age) have been overlooked in the research literature. The primary purpose of this study was to characterize the pre-season training habits of Masters-aged cross-country skiers using self-report training logs in order to develop more specific guidelines to improve future training practices. Methods: Masters cross-country skiers (24 men: (Mean±SD) 57 ± 8 yrs., 40-73 yrs.; 19 women: 55 ± 7 yrs., 40-69 yrs.) were recruited from the Pacific Northwest region. Over one 14-day data collection period (September-October, 2013), subjects were instructed to self-record all activity bouts in a spreadsheet-based training log. Activity bouts were classified into one of four categories by degree of cross-country ski training specificity: C1 = activities of daily living (ADL) and lowest specificity; C2 = low specificity (e.g., yoga); C3 = moderate specificity (e.g., running, cycling); C4 = highest specificity (e.g., roller skiing). Total time within each activity bout was recorded into self-assessed intensity zones: Z0 = minimal intensity; Z1 = low to moderate intensity; Z2 = high and race pace intensity; Z3 = above race pace intensity. Total time recorded in each category and training zone was evaluated using a two-factor RM ANOVA and Sheffe’s post-hoc test (0.05 alpha). Results: Total time self-reported within the logs was 12.4±2.1 hrs/wk. Total time (T) within C3 activities (TC3= 8.5±1.1 hrs/wk) was significantly higher (P\u3c0.001) than all other categories (1.5±0.4, 0.9±0.4, 0.6±0.4 hrs/wk for TC1, TC2, and TC4, respectively,). In addition, total time (T) in Z1 (TZ1= 6.3±0.9 hrs/wk) was significantly higher (P\u3c0.001) than other zone values (2.6±0.7, 2.4±0.4, 1.1±0.2 hrs/wk for TZ0, TZ2, and TZ3, respectively). Conclusion: These skiers tended to self-select low-moderate intensity training (Zone 1) that was predominantly low impact and moderate in specificity (Category 3) to cross country skiing. These preferences may reflect an avoidance of traditional high impact training (e.g., running), as well as high risk activities (e.g., roller skiing), while the Zone 1 preference may simply reflect a dominance of base training. These results indicate that the observed training habits differ from what is known to be optimal for elite and junior skiers (i.e. polarized training models) and may in fact be the optimal training to avoid high risk or high impact activities

RELIABILITY AND VALIDITY OF USING A HAND-HELD GPS MONITOR TO CONTROL OVERGROUND HIKING SPEED

T.K. Vetrone, L.Whalen, K.A. Pribanic, & D.P. Heil Montana State University, Bozeman, MT To accurately control locomotion speed and grade, load carriage studies are commonly performed in lab settings. However, it may be more appropriate to perform these same studies in outdoor settings. For example, a recent study in our lab assessed the energetic and kinematic effects of hiking with an armored tactical vest commonly worm by active military ground troops. To control outdoor hiking speed, a hand-held GPS monitor was used by investigators to pace the test subjects as they hiked a level trail under different load carriage conditions. The accuracy and repeatability of this technique for controlling outdoor hiking speed, however, has never been evaluated. PURPOSE: To determine the validity and reliability of using a hand-held GPS monitor to control overground hiking speed of subjects performing outdoor load carriage studies. METHODS: Nine women (mean±SD: 27±7 years; 163.1±6.1 cm; 62.5±10.3 kg) and eight men (24±4 years; 179.5±6.0 cm; 81.7±12.5 kg) performed outdoor hiking tests as part of a larger study of wearing a Modular Tactical Vest (MTV) both with and without a hip belt. The three hiking conditions (hiking without MTV; hiking with MTV; and hiking with MTV plus a hip belt) were each performed at three goal speeds: 67.0m/min (2.5mph); 80.4m/min (3.0mph); 93.8m/min (3.5mph), for a total of 9 trials. For each trial, subjects followed an investigator (i.e. pacer) with a hand-held GPS monitor with instructions to stay within 1-2 m of the pacer at all times. Actual speed for each lap was computed from the time required to complete each 293 m lap. Reliability of actual speed between the two laps was assessed using a two-factor repeated measures ANOVA (α=0.05), the intraclass correlation coefficient (Rxx), and the standard error of measurement (SEM). Validity was assessed by comparing the goal speeds to the 95% confidence intervals for each trial speed. RESULTS: Reliability results were mixed: ANOVA for all 9 trials were non-significant; Rxx values ranged from low to high (0.27-0.87); SEM for each of the 9 trials was consistently low (±0.47 to ±1.02 m/min; or ±0.02 to ±0.04mpg). Lastly, the goal speeds were all within the 95% CIs for each of the 9 trials. CONCLUSIONS: Based on the collective reliability and validity results, the method of using a hand-held GPS monitor to control overground hiking speed was both reliable and valid and should be considered for future outdoor overground locomotion studies

PREDICTING THE ENERGY COST OF STEEP UPHILL TREADMILL WALKING: A CROSS-VALIDATION

PREDICTING THE ENERGY COST OF STEEP UPHILL TREADMILL WALKING: A CROSS-VALIDATION E.Davila1, E.C. Ranta1, L.M. Whalen1, D. Weishar2, A. Blake2, D.E. Lankford2, & D.P. Heil, FACSM1. 1Montana State University, Bozeman, MT; 2Brigham Young University, Rexburg, ID INTRODUCTION: There are a growing number of commercially-available electronic monitoring devices that claim to predict the energy cost of exercising as a function of one or more predictive metrics. Devices relying upon global positioning satellite (GPS) data, for example, can predict the energy cost of walking and running outdoors by determining real-time changes in travel speed and surface incline. These data can then be combined with a laboratory-derived prediction algorithm, but the algorithm must include both steep uphill and downhill inclines to remain ecologically valid. A well-known formula by Minetti et al. (JAP 2002), considered valid for inclines between -45% and +45%, would seem well suited but does not appear to have been cross-validated in the literature. The purpose of this study was to cross-validate the original Minetti formula for predicting relative energy cost (CW, J/kg/m) between -5% and +30% for treadmill walking using a broad range of healthy adults. METHODS: 31 recreationally-active adults (18 men: (Mean±SD) 28 ± 8 yrs, 20-45 yrs, and 23.0±3.3, 21.0-34.4 kg/m2; 13 women: 29 ± 3 yrs, 25-35 yrs, and 23.1±2.8, 19.1-29.8 kg/m2) were recruited to walk on a treadmill at 53.6 m/min (2.0 MPH) at one of four lower inclines (-5%, -2.5%, 0%, +8%) and one of four steeper inclines (+15%, +19%, +22.5%, +30%) across four separate lab visits for 20 mins at each incline. Steady-state oxygen consumption (VO2), recorded via standard indirect calorimetry procedures, were averaged from the end of each 20-min test. Net VO2 (exercise VO2 – resting VO2) was then converted to CW using the measured non-protein RER, body mass, and treadmill speed. Predicted CW, as determined from the original Minetti formula, was compared to measured CW using a two-factor repeated measures ANOVA, including a comparison by gender, at each incline (0.05 alpha). RESULTS: Mean predicted CW was statistically similar between genders for both measured and predicted CW. In contrast, measured CW was significantly lower (P\u3c0.001) than predicted CW at the lower inclines (≤ +15%), statistically similar at the +19% incline, and significantly higher at the steepest inclines (+22.5% and +30%; P\u3c0.001). CONCLUSIONS: The Minetti formula for predicting CW for steep downhill and uphill walking was derived using well-trained men accustomed to mountain running. The present study, in contrast, used a more diverse adult population (i.e., recreationally active, men and women, wide range of BMI) which suggests that the Minetti formula may lack a broad generalizability for the range of inclines tested (-5% to +30%) for populations dissimilar to the original validation sample