If the demand for credit reduces, then so do interest rates. This is because there are more sellers than buyers, so buyers can command a lower better price, i.e. lower rates. A major factor driving interest rates is inflation. Higher inflation is associated with a growing economy. When the economy grows too strongly the Federal Reserve increases interest rates to slow the economy down and reduce inflation.
Inflation results from prices of goods and services increasing.
When the economy is strong there is more demand for goods and services, so the producers of those goods and services can increase prices. A strong economy therefore results in higher real-estate prices, higher rents on apartments and higher mortgage rates. Mortgage rates tend to move in the same direction as interest rates. However, actual mortgage rates are also based on supply and demand for mortgages. This might sometimes result in mortgage rates moving differently from other rates.