Paul M. Vanderburgh

Acute Effects of Whole-Body Vibration on Lower Extremity Muscle Performance in Persons With Multiple Sclerosis

Background and Purpose: Whole-body vibration (WBV) is a relatively new form of exercise training that may influence muscle performance. This study investigated the acute effects of high- (26 Hz) and low- (2 Hz) frequency WBV on isometric muscle torque of the quadriceps and hamstrings in persons with multiple sclerosis. Participants and Method: Fifteen individuals (mean age = 54.6 years, SD = 9.6) with multiple sclerosis and Expanded Disability Status Scale scores ranging from 0 to 6.5 (mean = 4.2, SD = 2.3) participated in this randomized, crossover study. After baseline measures of isometric quadriceps and hamstring muscle torque, subjects were exposed to 30 seconds of WBV at either 2 or 26 Hz. Torque values were measured again at one, 10, and 20 minutes after vibration. Subjects returned one week later to repeat the same protocol at the alternate vibration frequency. Results: There were no significant differences in isometric torque production between the 2- and 26-Hz WBV conditions. There was also no significant difference between baseline torque values and those measured at one, 10, and 20 minutes after either vibration exposure. However, there was a consistent trend of higher torque values after the 26-Hz WBV when compared with the 2-Hz condition for both quadriceps and hamstring muscles. Discussion and Conclusion: Although not statistically significant, peak torque values for both quadriceps and hamstring muscles were consistently higher after 30 seconds of WBV at 26 vs 2 Hz. Whether WBV presents a viable treatment option as either a warm-up activity or a long-term exercise intervention is yet to be determined. Future studies should include a wider variety of WBV parameters and the use of functional outcome measures.

Age, sex, and finish time as determinants of pacing in the marathon.

March, DS, Vanderburgh, PM, Titlebaum, PJ, and Hoops, ML. Age, sex, and finish time as determinants of pacing in the marathon. J Strength Cond Res 25(2): 386-391, 2011-Previous researchers have suggested that faster marathoners tend to run at a more consistent pace compared with slower runners. None has examined the influence of sex and age on pacing. Therefore, the purpose of this study was to determine the simultaneous influences of age, sex, and run time on marathon pacing. Pacing was defined as the mean velocity of the last 9.7 km divided by that of the first 32.5 km (closer to 1.0 indicates better pacing). Subjects were 186 men and 133 women marathoners from the 2005, 2006, and 2007 races of a midwestern U.S. marathon. The course was a 1.6 km (1 mile) loop with pace markers throughout, thus facilitating pacing strategy. Each 1.6-km split time was measured electronically by way of shoe chip. The ambient temperature (never above 5°C) ensured that hyperthermia, a condition known to substantially slow marathon times and affect pacing, was not likely a factor. Multiple regression analysis indicated that age, sex, and run time (p < 0.01 for each) were simultaneously independent determinants of pacing. The lack of any 2- or 3-way interactions (p > 0.05 for each) suggests that the effects of 1 independent variable is not dependent upon the levels of others. We conclude that older, women, and faster are better pacers than younger, men, and slower marathoners, respectively. Coaches can use these findings to overcome such tendencies and increase the odds of more optimal pacing.

Occupational Relevance and Body Mass Bias in Military Physical Fitness Tests

Recent evidence makes a compelling case that US Army, Navy, and Air Force health-related physical fitness tests penalize larger, not just fatter, service members. As a result, they tend to receive lower scores than their lighter counterparts, the magnitude of which can be explained by biologic scaling laws. Larger personnel, on the other hand, tend to be better performers of work-related fitness tasks such as load carriage, heavy lifting, and materiel handling. This has been explained by empirical evidence that lean body mass and lean body mass to dead mass ratio (dead mass = fat mass and external load to be carried/lifted) are more potent determinants of performance of these military tasks than the fitness test events such as push-ups, sit-ups, or 2-mile-distance run time. Because promotions are based, in part, on fitness test performance, lighter personnel have an advancement advantage, although they tend to be poorer performers on many tests of work-related fitness. Several strategies have been proposed to rectify this incongruence including balanced tests, scaled scores, and correction factors--yet most need large-scale validation. Because nearly all subjects in such research have been men, future investigations should focus on women and elucidate the feasibility of universal physical fitness tests for all that include measures of health- and work-related fitness while imposing no systematic body mass bias.

Considering body mass differences, who are the world's strongest women?

PURPOSE Allometric modeling (AM) has been used to determine the worlds strongest body mass-adjusted man. Recently, however, AM was shown to demonstrate body mass bias in elite Olympic weightlifting performance. A second order polynomial (2OP) provided a better fit than AM with no body mass bias for men and women. The purpose of this study was to apply both AM and 2OP models to womens world powerlifting records (more a function of pure strength and less power than Olympic lifts) to determine the optimal model approach as well as the strongest body mass-adjusted woman in each event. METHODS Subjects were the 36 (9 per event) current women world record holders (as of Nov., 1997) for bench press (BP), deadlift (DL), squat (SQ), and total (TOT) lift (BP + DL + SQ) according to the International Powerlifting Federation (IPF). RESULTS The 2OP model demonstrated the superior fit and no body mass bias as indicated by the coefficient of variation and residuals scatterplot inspection, respectively, for DL, SQ, and TOT. The AM for these three lifts, however, showed favorable bias toward the middle weight classes. The 2OP and AM yielded an essentially identical fit for BP. CONCLUSIONS Although body mass-adjusted world records were dependent on the model used, Carrie Boudreau (U.S., 56-kg weight class), who received top scores in TOT and DL with both models, is arguably the worlds strongest woman overall. Furthermore, although the 2OP model provides a better fit than AM for this elite population, a case can still be made for AM use, particularly in light of theoretical superiority.

Validation of the Wilks powerlifting formula

PURPOSE Because maximal strength varies with body mass, the International Powerlifting Federation (IPF) has adopted a method of adjusting powerlifting events (bench press, BP; squat, SQ; deadlift, DL, and total lift (the sum of BP, DL, and SQ), TOT) by body mass. This method, the Wilks formula, multiplies ones lift by an index based on body mass so that lifters of different size can be compared on the same event. The Wilks formula is not, however, based on published data and has yet to be critically evaluated. The purpose of this investigation, then, was to validate the Wilks formula. METHODS This was performed by 1) examining residuals bias to verify that the adjusted score does, in fact, lead to no systematic bias based on body mass and 2) by applying a more theoretically supportable allometric model to the same data and comparing the fit with the Wilks approach. Subjects were the current mens and womens world record holders as well as the top two performers for each event in the IPFs 1996 and 1997 World Championships (a total of 30 men and 27 women for each lift). RESULTS Results of data analysis regarding the Wilks formula indicate that: 1) there is no bias for mens or womens BP and TOT; 2) there is a favorable bias toward intermediate weight class lifters in the womens SQ with no bias for mens SQ; and 3) there is a linear unfavorable bias toward heavier men and women in the DL. Furthermore, the allometric approach indicated a bias against light and heavy men and women which may be considered acceptable given that half as many lifters are found in the lightest and heaviest weight classes as in the intermediate weight classes. CONCLUSION As used currently (BP and TOT only), the Wilks formula appears to be a valid method to adjust powerlifting scores by body mass.

Multivariate allometric scaling of men's world indoor rowing championship performance.

The World Indoor Rowing Championship (WIRC) is based on the time (T) to row a simulated 2500 m on a rowing ergometer. In the WIRC there are separate age categories but only two weight classes: light and heavyweight, thus penalizing those just heavier and those significantly lighter than the cut-off weight. Multivariate allometric scaling (MAS) provides an expression of performance free of the confounding effect of more than one scaling variable. We used MAS to scale T by height (H) and age (A) to create a new index of rowing performance, T*H(-a)*A(-b). Subjects were 148 male competitors from the 1995 WIRC. MAS indicated that T*H*A(-0.06) expresses T free of the confounding effect of H and A. We also scaled T only by H on those subjects, A < 40, (N = 109). Results showed that T*H is an optimal and particularly feasible scaling of T. Use of either convention dramatically changed race results. In conclusion, we recommend use of either the T.H (17 < or = A < or = 39) or T*H*A(-0.06) conventions to adjust WIRC performance in adult males.

Body Mass Penalties in the Physical Fitness Tests of the Army, Air Force, and Navy

Recent research has empirically documented a consistent penalty against heavier service members for events identical or similar to those in the physical fitness tests of the Army, Air Force, and Navy. These penalties, which are not related to body fatness, are based on biological scaling models and have a physiological basis. Using hypothetical cases, we quantified the penalties for men, with body mass of 60 vs. 90 kg, and women, 45 vs. 75 kg, to be 15% to 20% for the fitness tests of these three services. Such penalties alone can adversely affect awards and promotions for heavier service members. To deal equitably with these penalties in a practical manner, we offer two recommendations, i.e., (1) implementation of revised fitness tests with balanced events, in which the penalties of one event for heavier service members are balanced by an equal and opposite bias against lighter service members, or (2) development of correction factors that can be multiplied by raw scores to yield adjusted scores free of body mass bias.

Effects of Heat Stress and Sex on Pacing in Marathon Runners

Abstract Trubee, NW, Vanderburgh, PM, Diestelkamp, WS, and Jackson, KJ. Effects of heat stress and sex on pacing in marathon runners. J Strength Cond Res 28(6): 1673–1678, 2014—Recent research suggests that women tend to exhibit less of a precipitous decline in run velocity during the latter stages of a marathon than men when the covariates of age and run time are controlled for. The purpose of this study was to examine this sex effect with the added covariate of heat stress on pacing, defined as the mean velocity of the last 12.2 km divided by the mean velocity of the first 30 km. A secondary purpose of this investigation was to compare the pacing profiles of the elite men and women runners and the pacing profiles of the elite and nonelite runners. Subjects included 22,990 men and 13,233 women runners from the 2007 and 2009 Chicago marathons for which the mean ambient temperatures were 26.67° C and 2.77° C, respectively. Each 5-km split time was measured via an electronic chip worn on the participants’ shoe. Multiple regression analysis indicated that age, sex, heat stress, and overall finish time (p < 0.01 for each) were simultaneous independent elements of pacing. Nonelite women were consistently better pacers than nonelite men in both marathons, and this sex difference was magnified from cold to warm race temperatures. No difference (p < 0.05) in pacing was found between elite men and women runners. Elite men and women had enhanced pacing over their nonelite counterparts. In hotter temperatures, coaches of novice runners should advise their athletes to implement a slower initial velocity to maintain or increase running velocity later in the race.

Load-Carriage Distance Run and Push-Ups Tests: No Body Mass Bias and Occupationally Relevant

Recent research has demonstrated body mass (M) bias in military physical fitness tests favoring lighter, not just leaner, service members. Mathematical modeling predicts that a distance run carrying a backpack of 30 lbs would eliminate M-bias. The purpose of this study was to empirically test this prediction for the U.S. Army push-ups and 2-mile run tests. Two tests were performed for both events for each of 56 university Reserve Officer Training Corps male cadets: with (loaded) and without backpack (unloaded). Results indicated significant M-bias in the unloaded and no M-bias in the loaded condition for both events. Allometrically scaled scores for both events were worse in the loaded vs. unloaded conditions, supporting a hypothesis not previously tested. The loaded push-ups and 2-mile run appear to remove M-bias and are probably more occupationally relevant as military personnel are often expected to carry external loads.

Contributions of Body Fat and Effort in the 5K Run: Age and Body Weight Handicap

Crecelius, AR, Vanderburgh, PM, and Laubach, LL. Contributions of body fat and effort in the 5K run: age and body weight handicap. J Strength Cond Res 22(5): 1475-1480, 2008-The 5K handicap (5KH), designed to eliminate the body weight (BW) and age biases inherent in the 5K run time (RT), yields an adjusted RT (RTadj) that can be compared between runners of different BW and age. As hypothesized in a validation study, however, not all BW bias may be removed, because of the influences of body fatness (BF) and effort (run speed; essentially the inverse as measured by rating of perceived exertion (RPE)). This studys purpose was to determine the effects of BF and RPE on BW bias in the 5KH. For 99 male runners in a regional 5K race (age = 43.9 ± 12.1 years; BW = 83.4 ± 12.9 kg), BF was determined via sum of three skinfolds just before the race. RPE, on the 20-point Borg scale, was used to assess overall race effort on race completion. Multiple regression analysis was used to develop a new adjusted RT (NRTadj, the RTadj corrected for BF and RPE), which was computed for each runner and then correlated with BW to determine bias. Indicative of slight bias, BW was correlated with RTadj (r = 0.220, p = 0.029). Both BF (p = 0.00002) and RPE (p = 0.0005) were significant, independent predictors of RTadj. NRTadj was not significantly correlated with BW (r = 0.051, p = 0.61), but BF explained 90%, and RPE explained only 6%, of the remaining BW bias evidenced in the 5KH. The previous finding that the 5KH does not remove all BW bias is apparently accounted for by BF and not RPE. Because no handicap should be awarded for higher BF, this finding suggests that the 5KH, for men, appropriately adjusts for the age and BW vs. RT biases previously noted.