Exploring a Threshold Concept in Kinesiology 306 Course

In Fall 2015, the new 5-credit KIN 306 course was created by combining old KIN 306 and 301 classes (3-credits each). This is the first course completed by all students pursuing a major in Kinesiology. Prior to Fall 2015, all Kinesiology majors completed two separate introductory 3-credit courses KIN 301 and KIN 306. The old KIN 306 course introduced students to theories of measurement and evaluation and various health and sport related aspect of fitness. The KIN 301 course, introduced the process of conducting a systematic search of research literature on health and sport related aspect of fitness and it culminated in students completing a final review paper on topic of their choice written in American Psychological Association (APA) format. I attended the Backwards by Design Workshop to gain insights on a feasible way to comprehensively integrate the content across the two courses. In addition to the challenge of restructuring this course, it was the first time I was teaching a writing course and also in the quarter system. My goal was to identify strategies to address the challenges of integrating content of old KIN 306 and KIN 301 courses, ensuring the new KIN 306 course had strong writing and discipline-based components, and also addressing feasibility of teaching and assessing this content in the time constraint of a quarter system

Age-associated adaptations in lower limb motor patterns during walking and cycling

Muscular strength and power generating ability decline with advancing age. Older adults adapt their lower limb motor patterns to cope with these declines in muscle function. When mechanical demands approach limits of lower limb muscular capacity, motor patterns must be adapted to produce a desired movement. The term “motor pattern” is used to broadly represent the kinematic and kinetic profile of a person accomplishing a given task. Generally, these adaptations involve higher reliance on stronger proximal muscles to compensate for limitations or weakness of distal muscles. Three studies were conducted to examine factors affecting differences between older and young adults in lower extremity mechanics for walking and cycling. In the first two studies, the effects of physical activity status, walking speed, and step length on lower extremity motor patterns of older and young adults were examined. As walking speed and step length increased, lower extremity muscular effort, as reflected by joint moments and power, increased. Differences in motor patterns between older and young participants, were preserved for multiple speed and step length conditions. In general, older adults showed higher reliance on hip musculature to compensate for lower muscle strength of plantarflexors. Moreover, sedentary and older groups, who had lower leg strength, exhibited similar lower limb motor patterns during walking. Likewise, physically active and young participants, who had higher lower extremity strength, displayed similar lower limb motor patterns. Consistent with the 2008 Physical Activity Guidelines for Americans, these results suggest that adopting and maintaining a physically active life-style can help maintain walking abilities in older adults. When cycling at a submaximal intensities, both older and young participants showed higher reliance on muscles about the knee and had higher rates of energy cost for higher power outputs and cadences. Older adults had higher rates of energy cost and higher co-activation of thigh antagonistic muscles during cycling than young adults. The higher antagonist co-activation likely contributes to older adults higher energy cost. Considering all study outcomes, differences in motor patterns used by older and young adults were more apparent for walking than cycling. The less prominent age-related differences in cycling are likely related to its non-weight bearing characteristic, heavier reliance on hip and knee muscular effort, and the kinematically constrained nature of the cycling task

Effects of Age, Power Output, and Cadence on Energy Cost and Lower Limb Antagonist Muscle Co-Activation during Cycling

It is unknown if higher antagonist muscle co-activation is a factor contributing to higher energy cost of cycling in older adults. We determined how age, power output, and cadence affect metabolic cost and lower extremity antagonist muscle co-activation during submaximal cycling. Thirteen young and 12 older male cyclists completed 6-minute trials at four power output-cadence conditions (75W-60rpm, 75W-90rpm, 125W-60rpm, and 125W-90rpm) while electromyography (EMG) and oxygen consumption were measured. Knee and ankle co-activation indices were calculated using vastus lateralis, biceps femoris, gastrocnemius, and tibialis anterior EMG data. Net rate of energy cost of cycling was higher in older compared to young cyclists at 125W (p=0.002) and at 90rpm (p=0.026). No age-related differences were observed in the magnitude or duration of co-activation about the knee or ankle (p\u3e0.05). Our results indicated knee and ankle co-activation is not a substantive factor contributing to higher energy cost of cycling in older adults

Effect of Using a Counter-balanced Smith Machine on Performance Measurements for Concentric-Only Bench Press Throws

Bench press throws using a Smith machine are often used for assessment and training of upper body power. Concentric only bench press throws (CON-BT) provide important information on an individual’s ability to produce force from a static start. Smith machines often utilize a counter-balance weight system to reduce the net load on the barbell; however, it is not known how counter-balance weight affects measurements of performance during a CON-BT. PURPOSE: To examine the effect of a counter-balance weight on CON-BT performance measurements. METHODS: 24 men (age: 23 ± 3 years, height: 179 ± 6 cm, mass: 91 ± 17 kg, bench press 1-repetition maximum [1RM]: 107 ± 18 kg) performed 2 sets of 2 repetitions of CON-BT at 30% of their 1RM using a no counter-balanced (NCB) and a counter-balanced (CB) Smith machine. Total duration, peak power, peak force, and peak velocity were measured using a linear accelerometer attached to the barbell; peak ground reaction force (GRF) was measured using a force plate. For each condition, data from the repetition with the highest peak power was used for further analyses. Peak EMG was measured for the right pectoral, deltoid and triceps muscles and normalized using peak EMG in the 1RM. RESULTS: Measurements for peak barbell power (NCB: 1169 ± 260 W, CB: 938 ± 262 W) and force (NCB: 695 ± 129 N, CB: 577 ± 134 N) were significantly greater (p\u3c0.05) for NCB compared to CB. The total duration of CON-BT was shorter for NCB (0.62 ± 0.41 s) compared to CB (0.78 ± 0.50 s). The peak GRF showed a trend (p\u3c0.10) for being lower for NCB (884 ± 213 N] compared to CB [912 ± 190 N). Peak EMG and peak velocity were unaffected by the use of counter-balance weight. CONCLUSION: The use of a CB Smith machine reduced barbell performance measurements (peak power and peak force) but increased the peak GRF during a CON-BT. A counter-balance weight becomes ineffective and the net external load increases during the CON-BT when the barbell accelerates faster than the gravitational constant pulls on the counter weight, thus explaining the lower performance measurements found for CB

Use of Counter-balanced Smith Machine Affects Performance Measurements for Rebound Bench Press Throws

Rebound bench presses throws (RBT), often performed on a Smith machine, are used for assessment and training of upper body power. During a RBT, the stretch-shortening cycle potentiates performance in the concentric movement. Smith machines frequently utilize a counter-balance weight to reduce the net load on the barbell; however, the use of counter-balance weight affects measures of performance for RBT. PURPOSE: To evaluate how the use of a counter-balanced Smith machine affects performance measures for RBT. METHODS: Performance measures for the no counter-balanced (NCB) and counter-balanced (CB) RBT were assessed for 24 men (age: 23 ± 3 years, height: 179 ± 6 cm, mass: 91 ± 17 kg, bench press 1-repetition maximum [1RM]: 107 ± 18 kg). Each participant performed 2 sets of 2 repetitions of RBT for each condition at 30 % of their 1RM. Peak power, peak force, peak concentric and eccentric velocities, and duration of eccentric and concentric phases were measured using a linear accelerometer attached to the barbell; peak ground reaction force (GRF) was measured using a force plate. For each condition, data from the repetition with the highest peak power was used in further analyses. Peak EMG was measured for the right pectoral, deltoid and triceps muscles and normalized using peak EMG in the 1RM. RESULTS: Peak barbell measurements for power (NCB: 1220 ± 269 W, CB: 1069 ± 255 W), force (NCB: 906 ± 252 N, CB: 713 ± 143 N), and concentric (NCB: 2.54 ± 0.27 m•s-1, CB: 2.24 ± 0.32 m•s-1) and eccentric (NCB: -1.19 ± 0.46 m•s-1, CB: -0.95 ± 0.29 m•s-1) velocities were significantly (p\u3c0.05) higher for NCB compared to CB. The durations for the eccentric (NCB: 0.53 ± 0.16 s, CB: 0.64 ± 0.12 s) and concentric phases (NCB: 0.58 ± 0.58 s, CB: 0.77 ± 0.82 s), and peak pectoral EMG (NCB: 91 ± 21 % of 1RM, CB: 101 ± 24 % of 1RM) were lower for NCB compared to CB. Peak EMG for deltoid and triceps and peak GRF were unaffected by the use of counter-balance weights. CONCLUSION: The use of CB equipment resulted in reduced performance measurements (peak power, peak force, and peak eccentric and concentric velocities) for the RBT compared to NCB equipment. The lower peak eccentric stretch velocity likely resulted in a less effective stretch-shortening cycle for CB compared to NCB and thus helps explain the lower performance measurements found for CB

Binge Drinking Following Resistance Exercise: Effect on Muscle Power Recovery

Alcohol impairs recovery of isokinetic performance following muscle damaging resistance exercise but no knowledge exists regarding alcohol’s effect on recovery of performance in explosive isotonic movements following resistance exercise that induces only limited muscle damage. Purpose: To investigate the effect of alcohol on recovery from resistance exercise for explosive performance measures. Methods: Nine healthy men (Mean ± SD: 24.8 ± 3.2 years, 176 ± 7 cm, 86.4 ± 14.6 kg) completed 2 identical acute heavy resistance exercise tests (AHRET) separated by 1 week. The AHRET consisted of 6 sets of 10 repetitions of smith machine squats at 80% of 1-repetition maximum (1-RM) with 2 min of rest between sets. From 10-20 minutes post-AHRET participants consumed either 190 proof grain alcohol (EtOH) equal to 1.086 g of alcohol per kg lean mass (82-122 ml total) or no alcohol (Placebo) diluted in an artificially sweetened and calorie free beverage. The participants were blinded to conditions and the order of conditions was counter-balanced. Blood alcohol concentration (BAC) was measured using a breathalyzer. Sixty-five minutes pre-exercise, participants ingested a meal replacement beverage (33.5 kJ per kg body mass). Before the AHRET (PRE) and the following morning (AM), participants performed three high pulls and three bench press throws with 30% of 1-RM, and 10 consecutive vertical jumps, all at maximal effort. Peak power was measured for all exercises. Muscle soreness was measured using analog scales at PRE and AM. Results: BAC peaked 60-90 min post-exercise in all participants (0.084 ± 0.017 g·dl-1) on alcohol ingestion days. No effect of alcohol was found for peak power in the high pull (EtOH, PRE: 1658 ± 432 W, AM: 1659 ± 260 W; Placebo, PRE: 1599 ± 397 W, AM: 1579 ± 301 W), bench press throw (EtOH, PRE: 1120 ± 276 W, AM: 1105 ± 295 W; Placebo, PRE: 1119 ± 202 W, AM: 1089 ± 257 W), or vertical jump (EtOH, PRE: 52.6 ± 13.5 W·kg-1, AM: 48.5 ± 6.3 W·kg-1; Placebo, PRE: 52.2 ± 9.4 W·kg-1, AM: 47.9 ± 9.0 W·kg-1). Leg soreness increased moderately from PRE to AM with no difference between conditions. CONCLUSION: A moderate BAC does not appear to affect explosive upper or lower body power capability on the morning following a heavy squat session that induces only limited muscle damage

Mechanisms Affecting Bench Press Throw Performance while Using a Counter-Balanced Smith Machine

The use of a counter-balance weight system of a Smith machine affects measures of bench press throw performance. Twenty-four men performed bench press throws at 30% of their one-repetition maximum under four different conditions: 1) counter-balance and rebound movement (RC), 2) no counter-balance and rebound movement (RNC), 3) counter-balance and concentric only movement (CC), and 4) no counter-balance and concentric only movement (CNC). Peak power, force, and concentric and eccentric velocities were measured using a linear accelerometer; and peak ground reaction force (GRF) was measured using a forceplate. Peak measures for concentric and eccentric velocities showed that NCB> CB and RBT > CBT. Peak GRF measures showed CB > NCB and RBT > CBT. The lower performance measures for CB were likely due to an increase in the net external load when the barbell accelerates faster than the gravitational constant causing the counter-balance weight becomes ineffective

Age-associated adaptations in lower limb motor patterns during walking and cycling

Muscular strength and power generating ability decline with advancing age. Older adults adapt their lower limb motor patterns to cope with these declines in muscle function. When mechanical demands approach limits of lower limb muscular capacity, motor patterns must be adapted to produce a desired movement. The term “motor pattern” is used to broadly represent the kinematic and kinetic profile of a person accomplishing a given task. Generally, these adaptations involve higher reliance on stronger proximal muscles to compensate for limitations or weakness of distal muscles. Three studies were conducted to examine factors affecting differences between older and young adults in lower extremity mechanics for walking and cycling. In the first two studies, the effects of physical activity status, walking speed, and step length on lower extremity motor patterns of older and young adults were examined. As walking speed and step length increased, lower extremity muscular effort, as reflected by joint moments and power, increased. Differences in motor patterns between older and young participants, were preserved for multiple speed and step length conditions. In general, older adults showed higher reliance on hip musculature to compensate for lower muscle strength of plantarflexors. Moreover, sedentary and older groups, who had lower leg strength, exhibited similar lower limb motor patterns during walking. Likewise, physically active and young participants, who had higher lower extremity strength, displayed similar lower limb motor patterns. Consistent with the 2008 Physical Activity Guidelines for Americans, these results suggest that adopting and maintaining a physically active life-style can help maintain walking abilities in older adults. When cycling at a submaximal intensities, both older and young participants showed higher reliance on muscles about the knee and had higher rates of energy cost for higher power outputs and cadences. Older adults had higher rates of energy cost and higher co-activation of thigh antagonistic muscles during cycling than young adults. The higher antagonist co-activation likely contributes to older adults higher energy cost. Considering all study outcomes, differences in motor patterns used by older and young adults were more apparent for walking than cycling. The less prominent age-related differences in cycling are likely related to its non-weight bearing characteristic, heavier reliance on hip and knee muscular effort, and the kinematically constrained nature of the cycling task.</p

Effects of Age, Power Output, and Cadence on Energy Cost and Lower Limb Antagonist Muscle Co-Activation during Cycling

It is unknown if higher antagonist muscle co-activation is a factor contributing to higher energy cost of cycling in older adults. We determined how age, power output, and cadence affect metabolic cost and lower extremity antagonist muscle co-activation during submaximal cycling. Thirteen young and 12 older male cyclists completed 6-minute trials at four power output-cadence conditions (75W-60rpm, 75W-90rpm, 125W-60rpm, and 125W-90rpm) while electromyography (EMG) and oxygen consumption were measured. Knee and ankle co-activation indices were calculated using vastus lateralis, biceps femoris, gastrocnemius, and tibialis anterior EMG data. Net rate of energy cost of cycling was higher in older compared to young cyclists at 125W (p=0.002) and at 90rpm (p=0.026). No age-related differences were observed in the magnitude or duration of co-activation about the knee or ankle (p>0.05). Our results indicated knee and ankle co-activation is not a substantive factor contributing to higher energy cost of cycling in older adults.This article is published as Buddhadev,H.H., Martin, P.E. Effects of Age, Power Output, and Cadence on Energy Cost and Lower Limb Antagonist Muscle Co-Activation during Cycling. Journal of Aging and Physical Activity; 2018; pg.1-31. DOI: 10.1123/japa.2017-0400. Posted with permission.</p

Effects of Age and Physical Activity Status on Redistribution of Joint Work During Walking

During walking older adults rely less on ankle and more on hip work than young adults. Disproportionate declines in plantarflexor strength may be a mechanism underlying this proximal work redistribution. We tested the hypothesis that proximal redistribution is more apparent in older compared to young adults and in sedentary compared to active individuals over multiple walking speeds. We recruited 18 young (18-35 yrs) and 17 older (65-80 yrs) physically active and sedentary adults. Participants completed five trials at four walking speeds as marker positions and ground reaction forces were collected. Sagittal plane net joint moments were computed using inverse dynamics. Instantaneous joint powers for the ankle, knee, and hip were computed as products of net joint moments and joint angular velocities. Positive joint work was computed by integrating hip, knee, and ankle joint powers over time in early, mid, and late stance, respectively. Relative joint work was expressed as a percentage of total work. Isokinetic strength of lower limb flexor and extensor muscles was measured. Older adults had lower relative ankle (p=0.005) and higher relative hip (p=0.007) work than young adults for multiple speeds. Non-significant trends (pThis accepted article is published as Buddhadev HH, Martin PE. Effects of age and physical activity status on redistribution of joint work during walking. Gait and Posture. 2016;50:131–136. doi:10.1016/j.gaitpost.2016.08.034. Posted with permission </p