[ effects of acute L-carnitine supplementation on anaerobic threshold and lactate accumulation during an incremental exercise]

Appropriate nutrition is an essential prerequisite for effective improvement of athletic performance, conditioning, recovery from fatigue after exercise, and avoidance of injury. Nutritional supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting fields to provide a boost to the recommended daily allowance. The aim of this study was to investigate the effects of acute L-carnitine supplementation on anaerobic threshold and lactate accumulation during incremental exercise. The study was double-blind, randomized and crossover in design. The subjects were 12 randomly selected active male physical education students, 21.75 +/- 0.64 years old, with a mean body mass index [BMI] of 23.7 +/- 0.94, divided into 2 groups. They received orally either 2g of L-carnitine dissolved in 200 ml water plus 6 drops of lemon juice or a placebo [6 ml lemon juice dissolved in 200 ml water] 90 minutes before they began exercise on treadmill. They performed a modified protocol of Conconi test to exhaustion. Plasma lactate concentrations were recorded at rest and immediately after the test. One-way analysis of variance with repeated measurements was used for data analysis. The results showed that lactate accumulation immediately after exercise in the L-carnitine group [3.870 +/- 0.19] was significantly lower [p=0.000] than in the placebo [6.080 +/- 0.58] group. In addition, the intervention led to a higher increase [p=0.000] in the maximum oxygen consumption [50.54 +/- 1.48], as compared to the placebo group [45.16 +/- 1.51]. The data also showed that the length of time required to reach the anaerobic threshold was higher in the L-carnitin group [19.14 +/- 0.65, vs 16.00 +/- 0.28 for the placebo group]. There was no statistically significant difference between the 2 groups with regard to the respiratory exchange ratio. L-carnitine supplementation seems to cause a reduction in the blood lactate accumulation and delay anaerobic threshold in an incremental exercise, resulting in improved performance

Propagation and fruiting of pineapple [ananas comosus L. Merr.] throuth tissue culture techniques

Pineapple [Ananas comosus L. Merr. CV. Queen] was propagated through in vitro culture using stem-tip explants. The produced plantlets were hardened-off for 2 months and acclimatized for 3 months in peatmoss and sand mixes, then grown for 13 months [fruiting stage] under greenhouse conditions. In a preliminary experiment; it was indicated that NaOCL was the most efficient microbicidal and soaking explants in solutions of NaOCL [1.0 percent] for 20 min, HgCl2 [0.1 percent] for 30 sec and ethanol [70 percent] for 5 sec resulted in totally microbial-free explants [i.e., the best surface-sterilization method]. Culturing the microbial-free explants on MS [Murashige and Skoog]-basal media [liquid and solid] supplemented with different doses of benzyl-adenine [BA] showed that both media supplemented with BA [1.0 mg/1] were the best for multiplication, but the liquid medium appeared to be better than the solid. Transferring shootlets, regenerated on the best multiplication medium, to solid MS-basal medium contained MS salts at a half strength and supplemented with different doses of indole-butyric acid [IBA] or a-naphthalene-acetic acid [NAA] demonstrated that the medium supplemented with NAA [2 mg/1] was the best for rooting. The ex vitro growth of the rooted plantlets in different mixes of peatmoss and sand for 2 months under hardening-off conditions [hardening-off stage], revealed that the mix of 3 peatmoss and 1 sand was the best for growth and development. Therefore, plants were further grown for 3 months in this mix [acclimatization stage], then transplanted in the greenhouse soil under controlled conditions where flowers and fruits [1.65 +/- 0.45 kg/fruit] were developed after 11 and 13 months, from transplanting, respectively