Lloyd L. Laubach

Effects of Two Different Strength Training Modes on Motor Performance in Children

(2002). Effects of Two Different Strength Training Modes on Motor Performance in Children. Research Quarterly for Exercise and Sport: Vol. 73, No. 3, pp. 340-344.

Effect of specific gait modifications on medial knee loading, metabolic cost and perception of task difficulty

BACKGROUND The metabolic cost and cognitive demand of altering natural gait have not been well studied. The purpose of this investigation was to assess three modified patterns - toe out, ipsilateral trunk lean and a medial weight shift at the foot - on the basis of 1) medial knee joint load reduction, 2) metabolic cost of performance and 3) subject perception of task difficulty. METHODS 12 healthy individuals underwent 3 dimensional motion analysis and metabolic testing to assess the gait mechanics and energy expenditure of natural gait and the three experimental gait patterns, performed to a self-selected moderate degree. Walking speed was controlled. Perceived workload was assessed using the NASA Task Load Index. FINDINGS Trunk lean significantly reduced first peak knee adduction moment (↓32%, P<0.001) as well as KAM impulse (↓35%, P<0.001), but was costly in terms of energy expenditure (↑11%, P<0.001) and perceived workload (↑1178%, P<0.001). A moderate toe-out pattern significantly reduced the second peak knee adduction moment (↓32%, P<0.001) and KAM impulse (↓14%, P=0.026), but had no effect on the first peak. Conversely, toe-out was least demanding in terms of additional energy expenditure (↑2%, P=0.001) and perceived workload (↑314%, P=0.001). Medial shift did not reduce knee adduction moment. INTERPRETATION The prioritization of joint load reduction versus additional metabolic and cognitive demands could play a substantial role in the clinical decision making process of selecting a modified gait pattern.

Comparison of caloric expenditure in intermittent and continuous walking bouts.

This study compared the caloric expenditure of 30 consecutive minutes (30 minute) of moderate intensity walking with 3 intermittent 10-minute bouts (3 X 10 minutes) of moderate intensity walking in healthy, unfit men (40–49 years). Screening consisted of Vo2max testing, which was measured using the Balke graded exercise test. Criteria for participation in this study included a measured Vo2max less than 33.8 ml-kg-1.min-1 (<25th percentile for cardiorespiratory fitness). Twenty men participated in this study. Testing consisted of 4 trials with a minimum of 5 days between each trial. The 30-minute and 3 X 10-minute bouts were each performed twice to measure test-retest reliability. Once reliability was found, the 2 30-minute and the 2 3 X 10-minute trials were averaged for further data analyses; t-tests showed no significant differences in energy expenditure between 1 continuous 30-minute and the 3 X 10-minute walking bouts at 274 and 279 kcal (p = 0.09), respectively. Thus, 3 X 10-minute intermittent walking bouts throughout the day are equally beneficial, in terms of caloric expenditure, as 1 30-minute continuous walking bout.

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.

Derivation of an Age and Weight Handicap for the 5K Run

The adverse effect of increasing age and/or body weight on distance run performance has been well documented. Accordingly, nearly all five kilometer (5K) road races employ age categories and, sometimes, a heavier body weight classification. Problems with such conventions include small numbers of runners within older age categories and the advantage given to the lightest runners within each weight category. We developed a 5K Handicap (5KH), a model that calculates an adjusted run time based on the inputs of actual 5K run time, age, and body weight for men and women. This adjusted time, then, can be compared between runners of different ages and body weights. The purpose of this paper was to explain, in detail, the derivation of the 5KH formula using published theoretical and empirical findings on age, body weight and distance run time relationships. To our knowledge, the 5KH is the first such model and overcomes the problems associated with being heavier within one weight class and having too few runners in certain age categories. We are currently undertaking large-scale validation studies and evaluation of its race day implementation.

Body Mass Bias in a Competition of Muscle Strength and Aerobic Power

Recently, a fitness competition called the Pump and Run (PR) has been popularized. Composed of 2 events, a 5-km road race time (RT) in seconds and a maximal-repetition bench press (BPR) with resistance based on a percentage of body mass (M), the final score (RTadj) equals RT - 30(BPR). From published findings, the authors hypothesized that the PR would impose a bias against heavier competitors. Furthermore, the potential for age bias in this event has not been evaluated. Therefore, the purpose of this study was to investigate M and age bias in the PR for men and women. For 74 female and 343 male competitors in a large PR event, RT, BPR, M, and age were collected from official competition results. Two subsamples were randomly created from the original sample: the validation (VAL) (54 women and 258 men) and the cross-validation (CVAL) (20 women and 85 men). For the VAL sample, the RTadj showed significant bias against heavier runners (women r2 = 0.35; men r2 = 0.28; P < 0.01 for both) but no age bias (women r2 = 0.04; men r2 = 0.005; P > 0.05 for both). Using allometric modeling, the authors developed a set of M-based correction factors to be multiplied by each RTadj to yield new adjusted run times (NRTadj) that would be free of M bias. As applied to the CVAL sample, the NRTadj values virtually eliminated the M bias (women r2 = 0.04; men r2 = 0.002; P > 0.05 for both) of the current PR scoring system and retained the absence of age bias (women r2 = 0.02; men r2 = 0.0002; P > 0.05 for both). The authors recommend the use of the NRTadj scores for future PR competitions.

The dose-response relationship between lateral foot wedging and the reduction of knee adduction moment

BACKGROUND Lateral foot wedges represent a biomechanical intervention aimed at reducing medial knee loads. However, the effects of varying wedge amounts on biomechanical variables and orthotic comfort have not been systematically studied. Further, arch height may influence the comfort of laterally wedged devices. Therefore, the primary purpose of this study was to examine the effect of incrementally increasing lateral wedge amounts on knee adduction moment parameters and subjective comfort. The secondary purpose was to relate arch height measures to the comfort of the devices. METHODS Twenty-five healthy subjects underwent three-dimensional instrumented gait analysis testing using seven inclinations of lateral wedging (0°, 2°, 4°, 6°, 8°, 10°, 12°). Subjects reported comfort level for each orthotic condition. Arch heights were measured in standing and sitting, and rigidity index and stiffness were calculated. FINDINGS The knee adduction moment decreased with wedge amounts up to 6°, but more aggressive amounts did not yield additional reductions. Comfort ratings did not change from baseline until wedge amounts exceeded 8°. In addition, arch height measures, arch rigidity index and stiffness did not relate to the comfort of the orthotic device regardless of the wedge amount. INTERPRETATION Knee adduction moment decreased with mild wedge amounts while maintaining comfort. Wedge amounts greater than 6° yielded little additional mechanical benefit and amounts greater than 8° compromised comfort. It appears that 4°-6° of lateral wedging are optimal in regard to desirable biomechanical change and comfort level in healthy individuals.

The Effects of Backwards Running Training on Forward Running Economy in Trained Males.

Abstract Ordway, JD, Laubach, LL, Vanderburgh, PM, and Jackson, KJ. The effects of backwards running training on forward running economy in trained males. J Strength Cond Res 30(3): 763–767, 2016—Backwards running (BR) results in greater cardiopulmonary response and muscle activity compared with forward running (FR). BR has traditionally been used in rehabilitation for disorders such as stroke and lower leg extremity injuries, as well as in short bursts during various athletic events. The aim of this study was to measure the effects of sustained backwards running training on forward running economy in trained male athletes. Eight highly trained, male runners (26.13 ± 6.11 years, 174.7 ± 6.4 cm, 68.4 ± 9.24 kg, 8.61 ± 3.21% body fat, 71.40 ± 7.31 ml·kg−1·min−1) trained with BR while harnessed on a treadmill at 161 m·min−1 for 5 weeks following a 5-week BR run-in period at a lower speed (134 m·min−1). Subjects were tested at baseline, postfamiliarized, and post-BR training for body composition, a ramped V[Combining Dot Above]O2max test, and an economy test designed for trained male runners. Subjects improved forward running economy by 2.54% (1.19 ± 1.26 ml·kg−1·min−1, p = 0.032) at 215 m·min−1. V[Combining Dot Above]O2max, body mass, lean mass, fat mass, and % body fat did not change (p > 0.05). Five weeks of BR training improved FR economy in healthy, trained male runners without altering V[Combining Dot Above]O2max or body composition. The improvements observed in this study could be a beneficial form of training to an already economical population to improve running economy.

Body mass index associations between mother and offspring from birth to age 18: the Fels Longitudinal Study

Parental obesity is a known determinant of childhood obesity. Previous research has shown a strong maternal influence on body mass index (BMI) during infancy and early childhood.