Energy flow through the lower extremities in high school baseball pitching.

It is generally accepted that most of the energy transferred to the ball during a baseball pitch is generated in the trunk and lower extremities. Therefore, purpose of this study was to assess the energy flow through the lower extremities during a baseball pitch. It was hypothesised that the (stabilising) leading leg mainly transfers energy in a distal-to-proximal order as a kinetic chain while the (driving) trailing leg generates most energy, primarily at the hip. A joint power analysis was used to determine the rates of energy (power) transfer and generation in the ankles, knees, hips and lumbosacral joint (L5-S1) for 22 youth pitchers. Analyses showed that the leading leg mainly transfers energy upwards in a distal-to-proximal order just before stride foot contact. Furthermore, energy generation was higher in the trailing leg and primarily arose from the trailing hip. In conclusion, the legs contribute differently to the energy flow where the leading leg acts as an initial kinetic chain component and the trailing leg drives the pitch by generating energy. The actions of both legs are combined in the pelvis and passed on to the subsequent, more commonly discussed, open kinetic chain starting at L5-S1.

Energy generation, absorption, and transfer at the shoulder and elbow in youth baseball pitchers.

Performance during the baseball pitch is dependent on the flow of mechanical energy through the kinetic chain. Little is known about energy flow during the pitching motion and it is not known whether patterns of energy flow are related to pitching performance and injury risk. Therefore, the purpose of this study was to quantify energy generation, absorption, and transfer across the shoulder and elbow during the baseball pitch and explore the associations between these energetic measures, pitch speed, and traditional measures of upper extremity joint loading. The kinematics of 40 youth baseball pitchers were measured in a controlled laboratory setting. Energy flow between the thorax, humerus, and forearm was calculated using a segmental power analysis. Regression analyses revealed that pitch speed was best predicted by arm cocking phase shoulder energy transfer to the humerus and peak elbow valgus torque was best predicted by arm acceleration-phase elbow energy transfer to the forearm. Additionally, energy transfer across the shoulder and elbow generally exhibited the strongest correlations to pitch speed and upper extremity joint loads. These data reinforce the importance of energy transfer through the kinetic chain for producing high pitch speeds and provide descriptive data for energy flow during baseball pitching not previously found in the literature.

Hip Range of Motion and Strength and Energy Flow During Windmill Softball Pitching.

CONTEXT: Inadequate hip range of motion (ROM) and isometric strength (ISO) may interfere with energy flow through the kinetic chain and result in increased injury susceptibility. OBJECTIVE: To examine the relationship of hip ROM and ISO with energy flow through the trunk and pitching-arm segments during the windmill softball pitch in youth athletes. A subsequent purpose was to examine the relationship between energy flow and pitch speed. DESIGN: Descriptive laboratory study. SETTING: University research laboratory. PATIENTS OR OTHER PARTICIPANTS: A sample of 29 youth softball pitchers (age = 11.2 ± 1.3 years, height = 155.0 ± 10.4 cm, mass = 53.2 ± 12.6 kg). MAIN OUTCOME MEASURE(S): Bilateral hip internal-rotation and external-rotation (ER) ROM and ISO were measured. Net energy outflow and peak rates of energy outflow from the distal ends of the trunk, humerus, and forearm were calculated for the acceleration phase of the windmill softball pitch, and pitch speed was measured. RESULTS: Regression analysis revealed an effect of drive-hip ER ISO on the net energy flow out of the distal ends of the trunk (P = .045) and humerus (P = .002). Specifically, increased drive-hip ER ISO was associated with increased net energy outflow from the trunk to the humerus and from the humerus to the forearm. No significant effects of hip ROM or other hip ISO measures were observed. Additionally, pitchers who achieved higher peak rates of distal outflow tended to achieve higher pitch speeds. CONCLUSIONS: An association was present between drive-hip ER ISO and the net energy flow out of the distal ends of the trunk and humerus during the acceleration phase of the windmill softball pitch, emphasizing the importance of hip and lower body strength in executing the whole-body windmill pitch. Overall, energy-flow analysis is an interesting new way to analyze pitching mechanics and will aid in furthering our understanding of performance and injury risk in windmill softball pitching.

Effects of Hip Range of Motion and Isometric Strength on Energy Flow during Windmill Softball Pitching.

CONTEXT: Inadequate hip range of motion (ROM) and isometric strength (ISO) may interfere with energy flow through the kinetic chain and result in increased injury susceptibility. OBJECTIVE: To examine the relationship of hip ROM and ISO with energy flow through the trunk and pitching arm segments during the windmill softball pitch in youth athletes. A subsequent purpose was to examine the relationship between energy flow and pitch speed. DESIGN: Descriptive laboratory study. SETTING: University research laboratory. PARTICIPANTS: A sample of 29 youth softball pitchers (11.2±1.3 yrs.; 155.0±10.4 cm; 53.2±12.6 kg). MAIN OUTCOME MEASURE(S): Bilateral hip internal rotation (IR) and external rotation (ER) ROM and ISO were measured. Net energy outflow and peak rates of energy outflow from the distal ends of the trunk, humerus, and forearm were calculated for the acceleration phase of the windmill softball pitch, and pitch speed was measured. RESULTS: Regression analysis revealed a significant effect of drive hip ER ISO on the net energy flow out of the distal ends of the trunk (p=0.045) and humerus (p=0.002). Specifically, increased drive hip ER ISO was associated with increased net energy outflow from the trunk to the humerus and from the humerus to the forearm. No significant effects of hip ROM or other hip ISO measures were observed. Additionally, pitchers who achieved higher peak rates of distal outflow tended to also achieve higher pitch speeds. CONCLUSIONS: There is an association between drive hip ER ISO and the net energy flow out of the distal ends of the trunk and humerus during the acceleration phase of the windmill softball pitch, emphasizing the importance of hip and lower body strength in the execution of the whole-body windmill pitch. Overall, energy flow analysis is an interesting new way to analyze pitching mechanics and will aid in further understanding of performance and injury risk in windmill softball pitching.

A Comparison of Outcomes Following Laparoscopic and Open Hysterectomy With or Without Lymphadenectomy for Presumed Early-Stage Endometrial Cancer: Results From the Medical Research Council ASTEC Trial.

OBJECTIVES: Laparoscopic hysterectomy (LH) is increasingly used for the management of endometrial malignancy. Its benefits may be particularly pronounced as these women are more likely to be older or obese. The aim of this study was to determine whether outcomes for LH are comparable to the open hysterectomy (OH). DESIGN: This was a prospective cohort study nested within the multicenter ASTEC (A Study in the Treatment of Endometrial Cancer) randomized controlled trial (1998-2005). POPULATION: Women with presumed early endometrial cancer were included. METHODS: Laparoscopic hysterectomy was compared with OH with or without systematic lymphadenectomy. MAIN OUTCOME MEASURES: Overall survival, time to first recurrence, complication rates, and surgical outcomes were the main outcome measures. RESULTS: Of 1408 women, 1309 (93%) received OH, and 99 (7%) had LH. LH was associated with longer operating time (median, LH 105 minutes [interquartile range (IQR), 60-150] vs OH 80 minutes [IQR, 60-95]; P < 0.001) but 50% shorter hospital stay (median, LH 4 days [IQR, 3-5] vs OH 6 days [IQR, 5-7]). The number of harvested lymph nodes was similar (median, LH 13 [IQR, 10-16] vs OH 12 [IQR, 11-13]; P = 0.67). LH had fewer intraoperative and postoperative adverse events (9% difference, LH 21% vs OH 30%; borderline significance; P = 0.07). The rate of conversion to laparotomy for the LH group was high (27%). The median follow-up was 37 months. After adjusting for significant prognostic factors, the hazard ratio for overall survival in those who underwent LH compared with those who underwent OH was 0.67 (95% confidence interval, 0.31-1.43) (P = 0.30). CONCLUSIONS: Laparoscopic hysterectomy for early endometrial cancer is safe. Although it requires longer operating time it is associated with shorter hospital stay and favorable morbidity profile. Further studies are required to assess the long-term safety.

The impact of exercise training on conduit artery wall thickness and remodeling in chronic heart failure patients.

Exercise training is an important adjunct to medical therapy in chronic heart failure, but the extent to which exercise impacts on conduit artery remodeling is unknown. The aim of this study was to evaluate the impact of aerobic and resistance exercise training modalities on arterial remodeling in patients with chronic heart failure. We randomized 36 untrained subjects with chronic heart failure to resistance training (58.8 ± 3.5 years), aerobic training (61.3 ± 2.8 years), or an untrained control group (64.4 ± 2.4 years). Peak oxygen consumption during cycle ergometry increased after 12 weeks in both the resistance and aerobic training (P < 0.001) groups, but not in controls, whereas leg strength only increased after resistance training (P < 0.05). Brachial artery wall thickness decreased in the resistance training group (475 ± 10 versus 443 ± 13 µm; P < 0.01), whereas no changes were apparent in the aerobic or control groups. Brachial diameter increased by ≈6% and ≈5% in the aerobic training and resistance training groups (P < 0.01), with no change evident in the control group. The wall:lumen ratio consequently declined in the resistance training group at 12 weeks (0.121 ± 0.004 versus 0.107 ± 0.004; P < 0.01) and increased in the control group (0.111 ± 0.006 versus 0.121 ± 0.009; P < 0.05). No wall:lumen change was evident in the aerobic training group. Our findings suggest that exercise has a systemic impact on remodeling of conduit arteries in humans and that resistance exercise training may be advantageous in subjects with chronic heart failure in this regard.

Impact of age, sex and exercise on brachial and popliteal artery remodelling in humans.

OBJECTIVE: To examine the impact of age, sex and exercise on wall thickness and remodelling in the popliteal and brachial arteries. METHODS: We compared wall thickness, lumen diameter and wall:lumen ratios in the brachial and popliteal arteries of 15 young (Y, 25.4+/-0.8 yr; 7M 8W) and 16 older sedentary (OS, 58.8+/-1.1 yr; 8M 8W) subjects, with 12 of the OS group also studied following 12 and 24 weeks exercise training. RESULTS: Wall thickness and lumen diameter were higher in the popliteal than the brachial artery for both groups (P<0.05); wall:lumen ratio was similar between arteries. Comparison of the Y and OS groups revealed no impact on wall thickness, whereas diameter values were higher in OS subjects (P<0.05). Whilst there were no significant differences in wall thickness between men and women in the Y or OS groups, diameter was larger in men than in women for both arteries (P<0.05). After 24 weeks of training the wall thickness of both arteries decreased (P<0.01) and the wall:lumen ratio of the brachial (P<0.01) and the popliteal (P<0.05) decreased. CONCLUSION: The cross-sectional results suggest that ageing was associated with increased lumen diameter, although wall:lumen ratio remained unchanged. Wall:lumen ratio was higher in women than men, irrespective of subject age or the artery studied. This related primarily to differences in lumen diameter between the sexes, as wall thickness did not significantly differ between men and women. Our longitudinal data strongly suggest that exercise training is associated with beneficial effects on conduit artery wall thickness and wall:lumen ratio in both upper and lower limbs in humans.