Effects of strength and power training on neuromuscular adaptations and jumping movement pattern and performance

Effects of strength and power training on neuromuscular adaptations and jumping movement pattern and performance. J Strength Cond Res 26(12): 3335-3344, 2012-This study aimed at comparing the effects of strength and power training (ST and PT) regimens on neuromuscular adaptations and changes on vertical jump performance, kinetics, and kinematics parameters. Forty physically active men (178.2 +/- 7.0 cm; 75.1 +/- 8.6 kg; 23.6 +/- 3.5 years) with at least 2 years of ST experience were assigned to an ST (n = 14), a PT (n = 14), or a control group (C; n = 12). The training programs were performed during 8 weeks, 3 times per week. Dynamic and isometric maximum strength, cross-sectional area, and muscle activation were assessed before and after the experimental period. Squat jump (SJ) and countermovement jump (CMJ) performance, kinetics, and kinematics parameters were also assessed. Dynamic maximum strength increased similarly (p < 0.05) for the ST (22.8%) and PT (16.6%) groups. The maximum voluntary isometric contraction increased for the ST and PT groups (p < 0.05) in the posttraining assessments. There was a main time effect for muscle fiber cross-sectional area (p < 0.05), but there were no changes in muscle activation. The SJ height increased, after ST and PT, because of a faster concentric phase and a higher rate of force development (p < 0.05). The CMJ height increased only after PT (p < 0.05), but there were no significant changes in its kinetics and kinematics parameters. In conclusion, neuromuscular adaptations were similar between the training groups. The PT seemed more effective than the ST in increasing jumping performance, but neither the ST nor the PT was able to affect the SJ and the CMJ movement pattern (e.g., timing and sequencing of joint extension initiation).

Effects of strength and power training on neuromuscular variables in older adults

The purpose of this study was to compare the neuromuscular adaptations produced by strength-training (ST) and power-training (PT) regimens in older individuals. Participants were balanced by quadriceps cross-sectional area (CSA) and leg-press 1-repetition maximum and randomly assigned to an ST group (n = 14; 63.6 +/- 4.0 yr, 79.7 +/- 17.2 kg, and 163.9 +/- 9.8 cm), a PT group (n = 16; 64.9 +/- 3.9 yr. 63.9 +/- 11.9 kg, and 157.4 +/- 7.7 cm), or a control group (n = 13; 63.0 +/- 4.0 yr, 67.2 +/- 10.8 kg, and 159.8 +/- 6.8 cm). ST and PT were equally effective in increasing (a) maximum dynamic and isometric strength (p < .05), (b) increasing quadriceps muscle CSA (p < .05), and (c) decreasing electrical mechanical delay of the vastus lateralis muscle (p < .05). There were no significant changes in neuromuscular activation after training. The novel finding of the current study is that PT seems to be an attractive alternative to regular ST to maintain and improve muscle mass.

Herbicides in the upper Poxim River, Sergipe, and the risk of contamination of water resources

Increased agricultural activity in watershed areas has been causing concern over contamination by herbicides in agricultural areas. The problem becomes more important when contamination can affect water for human consumption, as happens with water from the Poxim river, which supplies the city of Aracaju, capital of the State of Sergipe. The aim of this study was to evaluate the risk of contamination by herbicides to both surface and groundwater in the upper sub-basin of the Poxim River, and to detect the presence of the active ingredients Diuron and Ametrine up-river from the sugar-cane plantations. Risk analysis was carried out using criteria from the Environmental Protection Agency (EPA), the GUS index, and the GOSS method. It was observed that several active ingredients are at risk of leaching, demonstrating the importance of monitoring the river to control both the quality of water and the frequency and volume of herbicides used in the region. Based on the results, monitoring was carried out bi-monthly from July 2009 to July 2010 at two sampling points. Water samples were analyzed in the laboratory, where the presence of Diuron and Ametrine was noted. Water quality in the Sub-basin of the Rio Poxim is being influenced by the use of herbicides in the region. There was an increase in herbicide concentration in the surface water during the rainy season, possibly caused by soil runoff.

Microbiological quality assessment of sand and water from three selected beaches of South Coast, Sao Paulo State, Brazil

This study aimed to assess the sanitary quality of water, and wet and dry sand from three beaches located in the South Coast region of Sao Paulo State, Brazil, selected taking into account the frequency of tourists and the water quality (good, fair and poor). Thirty-six water samples each of wet and dry sand and seawater were collected monthly over a period of one year and analyzed for fecal indicator bacteria (FIB: thermotolerant coliforms, Escherichia coli, and enterococci), presumptive Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and dermatophytes. The results revealed FIB concentrations more elevated in dry sand followed by wet sand and water. P. aeruginosa and presumptive S. aureus were detected with a similar frequency in water and sand samples, but maximum concentrations and geometric means were higher in dry sand. C. albicans was detected only in water samples whereas the dermatophyte Microsporum sp. was isolated exclusively from dry and wet sand samples. This evaluation showed also that the environment had a significant influence on P. aeruginosa but not on presumptive S. aureus concentrations. According to threshold values proposed in the literature for E. coli and enterococci dry sand densities, none of the beaches would be considered of sufficient quality for recreational activities.

Effect of humidity and solvent vapor phase on cellulose esters films

In the present study the effect of relative humidity (RH) during spin-coating process on the structural characteristics of cellulose acetate (CA), cellulose acetate phthalate (C-A-P), cellulose acetate butyrate (CAB) and carboxymethyl cellulose acetate butyrate (CMCAB) films was investigated by means of atomic force microscopy (AFM), ellipsometry and contact angle measurements. All polymer solutions were prepared in tetrahydrofuran (THF), which is a good solvent for all cellulose esters, and used for spin-coating at RH of (35 +/- A 5)%, (55 +/- A 5)% or (75 +/- A 5)%. The structural features were correlated with the molecular characteristics of each cellulose ester and with the balance between surface energies of water and THF and interface energy between water and THF. CA, CAB, CMCAB and C-A-P films spin-coated at RH of (55 +/- A 5)% were exposed to THF vapor during 3, 6, 9, 60 and 720 min. The structural changes on the cellulose esters films due to THF vapor exposition were monitored by means of AFM and ellipsometry. THF vapor enabled the mobility of cellulose esters chains, causing considerable changes in the film morphology. In the case of CA films, which are thermodynamically unstable, dewetting was observed after 6 min exposure to THF vapor. On the other hand, porous structures observed for C-A-P, CAB and CMCAB turned smooth and homogeneous after only 3 min exposure to THF vapor.

Stopping power and depth dose profile of H+ and He+ ion beams in hydroxyapatite thin films.

Hadron therapy is a promising technique to treat deep-seated tumors. For an accurate treatment planning, the energy deposition in the soft and hard human tissue must be well known. Water has been usually employed as a phantom of soft tissues, but other biomaterials, such as hydroxyapatite (HAp), used as bone substitute, are also relevant as a phantom for hard tissues. The stopping power of HAp for H+ and He+ beams has been studied experimentally and theoretically. The measurements have been done using the Rutherford backscattering technique in an energy range of 450-2000 keV for H+ and of 400-5000 keV for He+ projectiles. The theoretical calculations are based in the dielectric formulation together with the MELF-GOS (Mermin Energy-Loss Function – Generalized Oscillator Strengths) method [1] to describe the target excitation spectrum. A quite good agreement between the experimental data and the theoretical results has been found. The depth dose profile of H+ and He+ ion beams in HAp has been simulated by the SEICS (Simulation of Energetic Ions and Clusters through Solids) code [2], which incorporates the electronic stopping force due to the energy loss by collisions with the target electrons, including fluctuations due to the energy-loss straggling, the multiple elastic scattering with the target nuclei, with their corresponding nuclear energy loss, and the dynamical charge-exchange processes in the projectile charge state. The energy deposition by H+ and He+ as a function of the depth are compared, at several projectile energies, for HAp and liquid water, showing important differences.