The effects of in-season high intensity interval training on professional male soccer players' running performances, were investigated. Twenty-two subjects participated in two consecutive training periods of ten weeks. The first period was considered as a control period and was compared with a period where two high intensity interval training exercises were included in the usual training program. Intermittent runs consisted of twelve to fifteen 15-s runs at 120% of maximal aerobic speed alternated with 15-s of rest. Sprint repetitions consisted of twelve to fifteen all-out 40-m runs alternated with 30-s of rest. Results from the high intensity interval training have shown that maximal aerobic speed was improved (+8.1±3.1%; p<0.001) and that the time of the 40-m sprint was decreased (-3.5±1.5%; p<0.001), while no change in either parameters were observed during control period. This study shows that improvements in physical qualities can be made during the in-season period.

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This paper provides new empirical evidence on housing bubble timing, volatility spillover, and bubble contagion between Japan and its economic partners, namely, the United States, the Eurozone, and the United Kingdom. First, we apply a generalized sup ADF (GSADF) test to the quarterly price-to-rent ratio from 1970Q1 to 2018Q4 to detect explosive behaviors in housing prices. Second, we analyze the volatility spillover in housing prices between Japan and its economic partners using the multivariate time-varying DCC-GARCH model. Third, we assess bubble contagion by estimating a non-parametric model of bubble migration with time-varying coefficients. We document two historical bubble episodes from 1970 to 2018 in Japan’s housing market. Moreover, we find evidence of volatility spillover effects and bubble contagion between Japan’s real estate market and its most important economic partners during several periods. In this context of market integration, countries need to develop coordinated real estate policies to address the risk of global real estate bubbles.

Using quarterly housing price-to-rent ratios from 1970 to 2018, this paper investigated the presence of real estate bubbles at a national level in eight selected European countries, namely Belgium, France, Germany, Italy, the Netherlands, Portugal, Spain, and the United Kingdom. Then, we analyzed bubbles contagion among these countries. We applied the generalized sup ADF test developed by Phillips et al. (2015) to detect explosive behavior in house prices. Subsequently, we implemented the non-parametric model with time varying coefficients developed by Greenaway-McGrevy and Phillips (2016) to estimate bubbles contagion among European real estate markets. We found evidence of at least one historical bubble in all these countries, with Germany, the Netherlands, Portugal, and Spain currently experiencing a rising bubble. The results also suggest that bubbles are contagious between these real estate markets.

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