The anaerobic threshold (AT), the point at which lactic acid starts to accumulates in the muscles, is considered to be somewhere between 85% and 90% of your maximum heart rate (HRmax) .
Ultimately, Windows Defender might fail to update the definitions itself for whatever reason. In such cases you must either force a definition update by navigating to the designated tab of Windows Defender or by downloading and installing the latest signature definitions. The Windows Defender Definition Updates are offline packages containing the most recent antivirus signature for Windows Defender. Once installed, they will make sure your PC is safe from the latest known viruses, spyware, PUPs, and malicious files.
Updated: February 8, 2007. Windows Defender is real-time protection software used for the detection and mitigation of spyware and other potentially unwanted software. It helps protect computers running Windows Vista, Microsoft Windows XP with Service Pack 2 (SP2), or Windows Server 2003 with Service Pack 1 (SP1). Windows Defender can be configured and used by the computer user or local administrator, or it can be configured and maintained by the system administrator.