Heffernan KS, Fahs CA, Shinsako KK, Jae SY, Fernhall B. Heart rate recovery and heart rate complexity following resistance exercise training and detraining in young men. Am J Physiol Heart Circ Physiol 293: H3180-H3186, 2007. First published September 21, 2007; doi:10.1152/ajpheart.00648.2007.-The purpose of this study was to examine heart rate recovery (HRR) and linear/nonlinear heart rate variability (HRV) before and after resistance training. Fourteen young men (25.0 Ϯ 1.1 yr of age) completed a crossover design consisting of a 4-wk time-control period, 6 wk of resistance training (3 days/wk), and 4 wk of detraining. Linear HRV was spectrally decomposed using an autoregressive approach. Nonlinear dynamics of heart rate complexity included sample entropy (SampEn) and LempelZiv entropy (LZEn). HRR was calculated from a graded maximal exercise test as maximal heart rate attained during the test minus heart rate at 1 min after exercise (HRR). There was no change in SampEn, LZEn, or HRR after the time-control portion of the study (P Ͼ 0.05). SampEn (P Ͻ 0.05), LZEn (P Ͻ 0.05), and HRR (P Ͻ 0.05) increased after resistance training and returned to pretraining values after detraining. There was no change in spectral measures of HRV at any time point (P Ͼ 0.05). These findings suggest that resistance exercise training increases heart rate complexity and HRR after exercise but has no effect on spectral measures of HRV in young healthy men. These autonomic changes regress shortly after cessation of training.heart rate variability; entropy; parasympathetic; autonomic LOSS OF HEART RATE variability (HRV) and slow heart rate recovery (HRR) after exercise, indexes of cardiac autonomic function, are associated with increased risk for arrhythmia and other cardiovascular morbidities and mortality (9,11,47,48,51,53). Concomitantly, increased HRV and HRR are associated with improved prognosis and lower mortality related to cardiovascular disease (11,53). Numerous studies have shown that aerobic/endurance exercise training increases HRV and HRR (13,17,25,26,31,49). Far less is known regarding the effects of resistance training on autonomically mediated beatto-beat cardiac fluctuations and postexercise HRR.Cross-sectional studies have found faster HRR after exercise in strength-trained athletes than their sedentary peers (34), suggesting faster vagal reactivation and/or faster sympathetic withdrawal. No prospective studies have examined the effect of resistance training on HRR. Moreover, the limited evaluations of cardiac autonomic modulation using HRV do not support favorable adaptations. Spectrally decomposing HRV, Cooke and Carter (12) demonstrated no change in high-frequency (HF) power after a strength-training intervention, suggesting no change in cardiac parasympathetic modulation.However, a great deal of information in the HRV signal spectra is not solely harmonic. A certain degree of randomness or irregularity exists in the system (24). As such, use of linear methods alone to analyze beat-to-beat changes in heart rate re...

With aging and disease, there is a breakdown of the natural fractal-like organization of heart rate (HR). Fractal-like correlation properties of HR can be assessed with detrended fluctuation analysis (DFA). A short-time scaling exponent (alpha(s)) value of 1 is associated with healthy HR dynamics, whereas values that deviate away from 1, in either direction, indicate fractal collapse. The purpose of this study was to examine the effect of resistance exercise training (RT) on fractal correlation properties of HR dynamics. Resting ECG was collected at baseline, following a 4-wk time control period and 6 wk of RT (3 days per wk) in 34 men (23 +/- 1 years of age). Fractal properties of HR were assessed with DFA. There was no change in alpha(s) following either the time control period or RT (1.01 +/- 0.06 to 0.98 +/- 0.06 to 0.93 +/- 0.04, P > 0.05). Given the potential bidirectional nature of fractal collapse, subjects were retrospectively separated into two groups (higher alpha(s) and lower alpha(s)) on the basis of the initial alpha(s) by using cluster analysis. An interaction was detected for alpha(s) following RT (P < 0.05). There was no change in alpha(s) in either group following the time control, but alpha(s) increased following RT in the lower alpha(s) group (n = 18; 0.73 +/- 0.04 to 0.69 +/- 0.04 to 0.88 +/- 0.04) and alpha(s) decreased following RT in the higher alpha(s) group (n = 16; 1.20 +/- 0.04 to 1.24 +/- 0.04 to 0.98 +/- 0.04). In conclusion, RT improves fractal properties of HR dynamics.

Revision quadriceps tendon repair presents a challenging problem for the treating surgeon because of associated anatomic defects such as large tendon-gap deficits and preexistent poor tissue quality. Current methods for revision quadriceps tendon repair use tendon autograft, which may predispose to additional morbidity because the repair relies only on soft tissue fixation. In this Technical Note, we describe a technique for revision of a failed quadriceps tendon repair with a large tendon gap using a trapezoidal plug Achilles tendon allograft. This technique constitutes a safe and effective approach to revising failed primary quadriceps tendon repairs, is suitable for large-gap defects, and has the ability to withstand large force transmissions.

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Case:We present a case of a 48-year-old man with a subacute tear of his left rectus femoris, repaired using Achilles tendon allograft. After fixation distally to the patella using suture anchors and a Krackow suture technique, the allograft was fixed proximally to the remnant rectus femoris tendon with multiple sutures in a variety of stitch configurations. The patient recovered excellently, regaining near-normal flexion and an intact straight leg raise without an extensor lag.Conclusion:The literature regarding repair of subacute and chronic rectus femoris ruptures is limited. We provide an additional option for operative repair of subacute and chronic ruptures using Achilles tendon allograft.