Does power matter with ECT?

BACKGROUND: To assess the incidence of depressed inpatients requiring high output ECT and the response of this group compared with a group requiring standard output ECT. METHODS: We reviewed the records of 59 consecutive inpatients that were treated with bilateral ECT between January 2001 and January 2004. Diagnosis of major depression was based on DSM IV criteria. Response and remission to ECT (respectively defined as a 50% reduction in score and a score of < or = 7 on the Hamilton Rating Scale for Depression; HRSD) of both groups were compared. RESULTS: Of the 59 patients, 13 (22%) required high output ECT. These patients needed significantly more ECT treatments than patients in the standard dose group (16.4+/-7.1 versus 10.4+/-4.5; p=0.01). In total, 31 of 46 patients (67%) requiring standard output ECT and 11 of the 13 patients (85%) requiring high output ECT responded to ECT. This difference is not significant. LIMITATIONS: This study has a retrospective nature and a rather homogenous sample. CONCLUSION: In this study 1 in 5 of the depressed inpatients needs a high dose energy of bilateral ECT to induce an adequate seizure. The efficacy of ECT in these patients is similar to that in the standard dose group. Considering these facts, high output ECT devices should be available for use in routine clinical practice.     

Effect of countermovement on power–force–velocity profile

Purpose

To study the effect of a countermovement on the lower limb force–velocity (F–v) mechanical profile and to experimentally test the influence of F–v mechanical profile on countermovement jump (CMJ) performance, independently from the effect of maximal power output (P _max).

Methods

Fifty-four high-level sprinters and jumpers performed vertical maximal CMJ and squat jump (SJ) against five to eight additional loads ranging from 17 to 87 kg. Vertical ground reaction force data were recorded (1,000 Hz) and used to compute center of mass vertical displacement. For each condition, mean force, velocity, and power output were determined over the entire push-off phase of the best trial, and used to determine individual linear F–v relationships and P _max. From a previously validated biomechanical model, the optimal F–v profile maximizing jumping performance was determined for each subject and used to compute the individual mechanical F–v imbalance (Fv _IMB) as the difference between actual and optimal F–v profiles.

Results

A multiple regression analysis clearly showed (r ² = 0.952, P < 0.001, SEE 0.011 m) that P _max, Fv _IMB and lower limb extension range (h _PO) explained a significant part of the interindividual differences in CMJ performance (P < 0.001) with positive regression coefficients for P _max and h _PO and a negative one for Fv _IMB.

Conclusion

Compared to SJ, F–v relationships were shifted to the right in CMJ, with higher P _max, maximal theoretical force and velocity (+35.8, 20.6 and 13.3 %, respectively). As in SJ, CMJ performance depends on Fv _IMB, independently from the effect of P _max, with the existence of an individual optimal F–v profile (Fv _IMB having an even larger influence in CMJ).     

A single-session testing protocol to determine critical power and W′

Purpose

Critical power (CP), and the finite capacity to perform work above CP (W′), can be determined using a 3-min “all-out” cycling test (3MT). This protocol requires two laboratory visits: an incremental exercise test, followed by a 3MT on a separate day. The purpose of this study was to establish whether an incremental exercise test and a 3MT performed during a single laboratory visit can be used to accurately determine CP and W′.

Methods

Twelve participants completed two experimental protocols: (1) Combined protocol: an incremental exercise test followed by a 3MT, with 20 min of recovery between exercise bouts; and (2) Independent protocol: the conventional 3MT protocol, performed on a separate day.

Results

CP determined from the Combined (254 ± 117 W) and Independent (256 ± 118 W) protocols were not different (p = 0.40). Similarly, W′ was not different (p = 0.96) between the Combined (13.7 ± 3.9 kJ) and Independent (13.7 ± 4.5 kJ) protocols. Linear regression revealed a strong level of measurement agreement between the protocols for CP and W′, evidenced by high R ² values (≥0.85) and marginal standard errors of the estimates (CP = 5 W; W′ = 1.81 kJ).

Conclusion

A Combined protocol, consisting of an incremental exercise test followed by a 3MT, provides an accurate and valid method to determine an individual’s CP and, to a lesser extent, W′. Furthermore, this protocol permits the measurement of the gas-exchange threshold and peak O₂ uptake and, consequently, the moderate, heavy, and severe exercise-intensity domains may be defined within a single exercise-testing session.     

Determinants of maximal instantaneous muscle power in women aged 50–75 years

The present study aimed at analysing the age-related decline in maximal muscle power (W˙) in 52 sedentary healthy women aged between 50 and 75 years to determine whether force or velocity is the major determinant. Maximal muscle power was estimated from two types of vertical jumps, squatting (SJ) and counter‐movement (CmJ), performed on a force platform. It was obtained by measuring the vertical force (F _opt) applied to the body centre of gravity and calculating the corresponding vertical velocity ( _opt). An age-related decline in absolute W˙ was statistically significant in all the conditions examined and in both peak W˙ and average power ( ) values. The decrease in _opt was also statistically significant. Also F_opt declined but this reduction was not statistically significant with the exception of the average value in CmJ. Not surprisingly the highest W˙ were obtained in CmJ, and the difference in power production between the two types of jump showed an age-related decrement only in . The main finding of the study was the demonstration that _opt was the critical determinant of the age-related decline in W˙ in healthy elderly women.     

Where will I plant my potatoes? Development and the power to decide

“Development” all over the world has been thrust upon unwilling victims. In some cases, well-meaning researchers have tried to engage local owners in “participatory” projects where indigenous knowledge is invited to lead efforts to increase a reliable food supply and provide some of the benefits of a cash economy. Unfortunately, the clear assertions of local people, anthropologists, nongovernmental organizations, and common sense have rarely held out against the power of corporations. In this paper I look at examples, some that bring despair and others that give hope to people trying to maintain not only their identities but also their lives.     

Chronic β-blockade does not influence muscle power output during high-intensity exercise of short-duration

Summary Patients receiving -receptor antagonists for the treatment of hypertension frequently complain of impaired exercise tolerance. To determine whether these medications impair skeletal muscle contractile function, we measured isokinetic muscle function in ten healthy male cyclists receiving nebivolol (N), atenolol (A), propranolol (P) and the calcium channel antagonist diltiazem (D). The subjects performed standardized tests of muscle power on an isokinetic cycle ergometer following subacute ingestion of N, A, P, D and placebo (PL) in a double blind crossover trial. Subjects exercised maximally for 10 s at 90, 110, 120, 130 and 150 rpm with 2-min rest between sessions. Thereafter, they performed a 30-s fatigue test at 120 rpm. Resting heart rate was decreased 13.4%, 21.9% and 14.6% by N, A and P, respectively (P<0.05 vs PL). Resting systolic blood pressure was decreased 6.7% by A only (P < 0.05 vs PL). Peak power, average power and work done was not different among treatment groups at any crank velocity, nor was there any difference in total work done or rate of work decline in the 30-s test. We concluded from our study that peak isokinetic muscle power during maximal exercise of short duration is not affected by -blockade or the calcium antagonist diltiazem. Fatigue during -receptor antagonism would not appear therefore to be due to changes in the ability of skeletal muscle to produce peak power output during exercise of short duration.     

A comparison of modelling procedures used to estimate the power–exhaustion time relationship

This study aimed to test the consistency of using the power required to elicit maximal oxygen uptake during incremental test (P _t) to demarcate the range of power intensity in the modelling of the power–exhaustion time relationship. Different mathematical procedures were tested using data from ten subjects exercising on a cycle ergometer. After the determination of P _t and the power at the ventilatory threshold, the subjects did six tests at constant power to exhaustion within 2–15 min. Estimates were obtained from a segmented model using two distinct equations of the anaerobic contribution to power below and above P _t, respectively. This model fit the overall data with a better adequacy than the simple hyperbolic model (standard error of 29.2 ± 25.2 vs. 42.3 ± 25.2 s). The power asymptotes were 225.7 ± 27.3 W from the segmented model, 226.2 ± 27.3 and 283.3 ± 20.5 W from the simple model applied to data below and above P _t, respectively. The estimates from the segmented model were strongly correlated with their analogues from the simple model applied only to data below P _t (R = 1.00 for power asymptote and curvature coefficient). They were not correlated with their analogues from the simple model applied only to data above P _t. These discrepancies between modelling procedures could arise from the method used to determine P _t and the oversimplification of the oxygen uptake kinetics. These limitations could lead the segmented model to an overestimation of the anaerobic contribution which was around 15% of total energy expended at P _t.     

Predictors of maximal short-term power outputs in basketball players 14-16 years

Relationships between growth, maturation and maximal short-term power outputs were investigated in 94 youth basketball players aged 14–16 years. Data included chronological age (CA), skeletal age (SA), years of training; body dimensions, estimated thigh volume, a running based short-term exercise assessed by the line drill test (LDT), the Bangsbo sprint test (BST) and short-term muscle power outputs with the Wingate anaerobic test (WAnT). Multiple linear regression analyses were used to estimate the effects of CA, skeletal maturity (SA/CA), years of training experience, body size and lower-limb volume on short-term performance in the LDT, BST and WAnT, respectively. Explained variances differed between cycle-ergometry outputs (52–54%) and running test performances (23–46%). The independent effects of predictors were small in the fatigue scores of the WAnT (4%) and the BST (11%). Skeletal maturity, body mass and leg length were primary predictors for all maximal short-term power output measures. Leg length was more relevant as a predictor than stature in the WAnT outputs, while stature and body mass appeared in the model with the running tests as dependent variable. Maximal short-term running abilities were also sensitive to years of training. In summary, skeletal maturation, body size and thigh muscle mass explained moderate to large proportions of the variance on maximal short-term performances of adolescent basketball players. The results highlight the importance of considering maturity status in evaluating the maximal short-term power outputs of adolescent athletes.     

Influence of initial metabolic rate on the power–duration relationship for all-out exercise

A single 3-min all-out cycling test can be used to estimate the power asymptote (critical power, CP) and the curvature constant (W') of the power-duration relationship for severe-intensity exercise. It was hypothesized that when exercise immediately preceding the 3-min all-out test was performed CP would systematically reduce the W' without affecting the CP. Seven physically active males completed 3-min all-out cycling tests in randomized order immediately preceded by: unloaded cycling (control); 6-min moderate; 6-min heavy; 2-min severe (S2); or 4-min severe (S4) intensity exercise. The CP was estimated from the mean power output over the final 30 s of the test and the W' was estimated as the power-time integral above end-test power. There were no significant differences in the CP between control (279 ± 62), moderate (275 ± 52), heavy (286 ± 66 W), S2 (274 ± 55), or S4 (273 ± 65 W). The W' was significantly lower (P < 0.05) in S2 (11.5 ± 2.5) and S4 (8.9 ± 2.2) than in control (16.3 ± 2.3), moderate (17.2 ± 2.4) and heavy (15.6 ± 2.3 kJ). These results support the notion that the W' is predictably depleted only at a power output >CP whereas the CP is independent of the mechanisms which reduce W'.     

Ventricular activity cancellation in electrograms during atrial fibrillation with constraints on residuals’ power

During atrial fibrillation (AF), cancellation of ventricular activity from atrial electrograms (AEG) is commonly performed by template matching and subtraction (TMS): a running template, built in correspondence of QRSs, is subtracted from the AEG to uncover atrial activity (AA). However, TMS can produce poor cancellation, leaving high-power residues. In this study, we propose to modulate the templates before subtraction, in order to make the residuals as similar as possible to the nearby atrial activity, avoiding high-power ones. The coefficients used to modulate the template are estimated by maximizing, via Multi-swarm Particle Swarm Optimization, a fitness function. The modulated TMS method (mTMS) was tested on synthetic and real AEGs. Cancellation performances were assessed using: normalized mean squared error (NMSE, computed on simulated data only), reduction of ventricular activity (VDR), and percentage of segments (PP) whose power was outside the standard range of the atrial power. All testings suggested that mTMS is an improvement over TMS alone, being, on simulated data, NMSE and PP significantly decreased while VDR significantly increased. Similar results were obtained on real electrograms (median values of CS1 recordings PP: 2.44 vs. 0.38 p < 0.001; VDR: 6.71 vs. 8.15 p < 0.001).     

Influence of road incline and body position on power–cadence relationship in endurance cycling

In race cycling, the external power-cadence relationship at the performance level, that is sustainable for the given race distance, plays a key role. The two variables of interest from this relationship are the maximal external power output (P (max)) and the corresponding optimal cadence (C (opt)). Experimental studies and field observations of cyclists have revealed that when cycling uphill is compared to cycling on level ground, the freely chosen cadence is lower and a more upright body position seems to be advantageous. To date, no study has addressed whether P (max) or C (opt) is influenced by road incline or body position. Thus, the main aim of this study was to examine the effect of road incline (0 vs. 7%) and racing position (upright posture vs. dropped posture) on P (max) and C (opt). Eighteen experienced cyclists participated in this study. Experiment I tested the hypothesis that road incline influenced P (max) and C (opt) at the second ventilatory threshold ([Formula: see text] and [Formula: see text]). Experiment II tested the hypothesis that the racing position influenced [Formula: see text], but not [Formula: see text]. The results of experiment I showed that [Formula: see text] and [Formula: see text] were significantly lower when cycling uphill compared to cycling on level ground (P < 0.01). Experiment II revealed that [Formula: see text] was significantly greater for the upright posture than for the dropped posture (P < 0.01) and that the racing position did not affect [Formula: see text]. The main conclusions of this study were that when cycling uphill, it is reasonable to choose (1) a lower cadence and (2) a more upright body position.